VW Baywindow Bus - The Great Oil Debates

by Richard Atwell
(c) Copyright 2020-2021


I've collected together a number of oil-based topics that always seem to elicit the fiercest online arguments and you can read my opinion on these topics below:

Part 1: Mythbusting

Part 2: Oil Additives

Companion Articles:

Part 1: Synthetic Oil

Synthetic oils offer protection against higher oil temperatures (e.g. at 300F) than conventional mineral oils can attain. Most conventional oils begin to break down before reaching 250F which is well within the reach of the air-cooled engine's operating temperature on a hot day. This characteristic is primarily due to the homogeneous design of the oil: the molecules are more uniform as a result of the refining process.

Viscosity is very important to lubrication and synthetic oils typically outpace conventional oils (YouTube). In general, synthetics:

  1. pour more easily at lower temperatures
  2. retain their viscosity for longer
  3. have higher flash points to prevent burn-off

Let's address the often cited objections to using synthetic oils:

Objection #1: Cost

Straight out of the bottle, comparing synthetics to mineral based oils, synthetics simply perform better but this comes at an increased cost that some argue isn't worth paying, justifying that you are better off simply changing your oil more often.

Discounts thru Costco/Sam's Club used to mean you could purchase 6-pack of Mobil 1 15W-50 for $22 USD but since Hurricane Katrina I've noticed that the difference in price between the warehouse clubs and the auto parts stores has diminished.

Back in 2003, 1 qt. of Mobil 1 15W-50 cost about $6-7 on the auto parts shelf. "Boutique" synthetics from other companies like Redline, Amsoil, Royal Purple and others tended to cost 2-3x per quart.

Today, the price gap between the boutique synthetics and the "big oil" synthetics on the store shelf has shrunk. Even Amazon Basics is getting into the market with their own branded synthetic which I think will help keep the prices in check.

In my experience, cost becomes a non-issue if you shop for sales of 5L jugs. Compare an individual bottles costing $15/L to a 5L jug for $27 (or $5.40/L). It's not always stocked in the grade you need but often available online or sometimes by special order.

I have seen 5L jugs of Valvoline 10W-30 for $10 in the past (2010) and the same size jug of Castrol 10W-40 at Walmart today (2020) can be had for $17 on sale.

Some synthetics are sold as blends of synthetic and regular mineral based oils but my advice is to spring for the full synthetics to obtain the longest lasting benefits.

The VW air-cooled engine will always consume some oil in the combustion chamber by design and I only seem to burn oil on long highway trips. Given that a 5 year old water-cooled Audi does the same thing, I don't think this is an issue especially if you purchase a synthetic oil on sale which is the ONLY time I ever purchase it.

Objection #2: Leaks

Do Synthetics cause leaks? They have been known to do so on older engines with old seals because the molecules were blamed for being "slightly smaller" or because of the fact that the oil and seals were similar in composition (both ester based for example).

Sometimes this caused the seals to swell or lose tensile strength and thus a leak occured. Other times because synthetics have been blamed for cleaning away the residues left by conventional oils or dislodging a contaminant that was an aid to sealing caused a leak. This is probably related to a better dispersants and detergents package which isn't necessarily limited to synthetic oils.

Oil additives can tailored to condition seals. For example, most high mileage oils have increased levels of seal swelling agents to help prevent leaks which are typical as an engine ages.

I personally have not experienced any of these problems when I switched from conventional oil at 60,000 miles.

One area where you'll notice oil seal issues is where the push rod tubes are sealed. I replaced the push rod tube seals around the same time as I switched to synthetic oil as the seals were already leaking on me with conventional oil. The black seals had gone brittle and the orange seals had become spongy.

Since switching to synthetic, I have not had any leaks in the last 16 years using the green Viton push rod tube seals that are preferred by VW/914 owners.

Objection #3: My Engine Leaks or Burns Oil

Problem: "I already have a leaky engine than burns a lot of oil and it's more economical to waste non-synthetic oil".

Solution: The cost a few seals and a little elbow grease often goes a long way towards saving oil. If the rings are bad, I can understand the objection.

Objection #4: Engine Break-In

If you are building a new engine, most people recommend you break in the engine with conventional oil and then switch to synthetic after the break in period. Good advice? Yes AND No.

Specifically, you should be using the break-in oil recommended by the camshaft manufacturer or engine rebuilder as per their warranty.

During initial start-up after a rebuild consider that:

Once this initial break-in has taken place the debate becomes whether or not it's risky to use a synthetic oil for the first 500 miles of driving?

Consider that the auto manufactures often factory fill their engines with synthetic oil and those engines can last hundreds of thousands of miles...

My advice is to use a quality synthetic oil with a suitable additive package for your VW engine (ZDDP, etc) that is already engineered into the formula (no pour-in additives) and to at least follow VW's recommendations for oil service which includes the summer/winter maintenance schedule.

Objection #5: Heat Retention

Gene Berg GB801

To the best of my knowledge, this one originated with the legendary Gene Berg company who wrote:

Note 2: We do not sell or use synthetic engine oil for the air-cooled VW as it rejects heat. The air cooled VW depends on the oil to soak up the heat from the head and carry it back to the oil cooler. With the synthetic oil the head temperature goes up and the oil temperature went down.

I am doing some testing on a new development in the synthetic engine oil that is advertised to pick up heat from the oil and take it to the cooler without viscosity break down. I will let you know in the future if it lives up to its claims.

This quote dates back to at least to a 1999 archive of their website and the very same quote still appears at the latest website.

I have checked to see if his Book of Technical Articles (GB 801) contains any background on this issue but there is none. This book dates back to the early 1980's and is still available and I'm wondering when this opinion on synthetic oil was published.

We don't know what brand of oil was used or the weight. We don't know if it was API certified. Given that Amsoil was certified in 1972, then Mobil in 1974, then Chevron in 1990 and Valvoline in 1992, we still have no clue. Maybe the viscosity of the oil was thicker, ran at a higher oil pressure and a higher oil temperature as a result? We just don't know!

All we can assume is that at one time Gene tried a very early synthetic oil. We also never received the promised follow-up to try again with a newer formula.

Without any details and given that this information is now 20-40 years out of date, we have to throw this one out as being unverifiable despite the highly regarded reputation of the source.


  1. Cost: buy jugs of synthetic oil at Walmart
  2. Leaks: replace old seals
  3. Oil Burning: burn less oil by using synthetic!
  4. Break-in: just follow the engine builder's requirements
  5. Heat: no data, inconclusive and debunked for now...

Brand X vs. Brand Y:

You'll often hear arguments against putting Brand X in your engine, or you'll hear that synthetics retain heat and cause leaks or other such comments.

Keep in mind that few people have actually experienced these problems and most are simply passing on what they've heard or read as HEARSAY. Even when there is a gain of truth in these statements you have to understand the context in which they were made and when this is lost the claims or statements have little value.

When a so-claimed catastrophic failure occurs due to Brand X, quite often that tip is passed along with no mention of the oil-change interval or climate or engine condition. Was the oil changed after 20k miles? Was it too thick to begin with? And what about the application: oil that is good for the drag racer may be no good for your daily driver. Was the vw bus engine abused before it failed?

Naturally, a lot of old school knowledge about oil brands and grades percolates down to the younger generations sometimes because of genuine good/bad experiences in the past with products that are no longer even available. Is Brand Y oil really as good or not as good as it used to be? Is the recommended oil brand even formulated the same way it was 30 years ago? If the crude oil comes from Pennsylvania is it still better than everything else in 2020 or just more marketing?

IMHO, not a lot can be gleaned about the performance of various oils in the VW engine by listening to the experience of other people. For every group of owners that have had a good experience, there is an equally large group who have had a bad one but more often than not people tend to stick with the brand that works for them and/or follow the herd.

Also consider that there are hundreds of oils in the marketplace but even with online shopping a lot of recommended oils simply are unavailable in the local marketplace, too expensive to ship to your home or export restricted by manufacturer.

Decide for Yourself:

Some brands do indeed perform better than others but in my experience, most claims are more about post purchase feelings vs. genuine results and most advice is too polarizedto be of use.

Oil formulations VARY GREATLY by brand: picking the one that fits your driving habits and budget just takes a little investigation:

  1. Download the Product Data Sheets for the desired oil brands/grades
  2. Make sure it's API rated
  3. Contact the oil company to verify the ZDDP levels
  4. Perform your own pour test at 0C (or the coldest winter temp in your climate)
  5. Lean towards using a multi-grade synthetic oil
  6. Keep a mileage record between oil changes
  7. Send the oil to an analysis lab for $30 to gauge viscosity breakdown, metal contamination and TBN degradation (acid resistance) and P/Zn levels

That may seem like a lot of work but compared to the time and effort you've put into your bus for other things why not give the engine some TLC? It's also going to give your results that are relevant for you.

There are countless videos on YouTube demonstrating the viscosity differences between brands. This test below was done @ -20C using 5W-30:

There are similar "bake-offs" where oils are subjected to 400C heat to see if/how they solidify. Many of these tests are done to brands that are only available in foreign countries but worth a look see...

Oil is the lifeblood of the engine. Anything you can do to extend into the future the rebuilding of the engine will be a worthwhile investment. With a little research online you'll be able to narrow your choice by eliminating the lesser performing brands.

Beware YouTube Timken Tests:

YouTube is awash in engine oil shootouts such as the ones at the Project Farm Channel (YouTube).

Another 16-oil shootout has been done by Nates Interactive Auto (YouTube) and I'm sure there are many others out there...

After logging countless minutes watching these entertaining videos, how are those 5W-30 and 10W-30 tests going to determine the winning brand for any 10W-40 or 20W-50 grade oil?

While seeing how oil flow compares under freezing conditions is interesting to observe, I believe these rudimentary bearing wear tests should be performed at startup temperature and at the operating temperature rather than these quasi cold-start conditions. They also fail to simulate the oil moving through an oil pump or against a camshaft lobe and are more akin to a rod bearing simulation (emphasis on the word simulation).

These videos are certainly entertaining but are just isolated data points. They should be taken as such and while a step above infomercials for pour-in-additives, the methodology is amateur and does not accurately simulate wear within an running engine.

Such tests may predict the performance of oils under extreme pressure conditions that cam lobes experience or it may not because this style of test "was developed to test industrial oil performance for roller bearings under extreme load" and "test repeatability is very poor" according to Pennzoil.

All you can conclude is which 5W-30 oil won the test and cross your fingers that the oil that produced the smallest wear scar will indeed work the best inside your engine.

Part 2: Oil Additives

Usually fall into these categories:

  1. Friction modifiers: PTFE, MoS2 ("moly"), ceramics
  2. Thickeners: e.g. Marvel Mystery Oil, Lucas Oil Stabilizer, etc. (which is basically 110 weight oil)
  3. Solvent-based: engine noise reducers to "complete" engine flushes

If you change your oil according VW's guidelines, you should never have a need for any of these types of additives. However, if the oil change interval is way overdue and/or unknown to you or the engine has been sitting for a length of time AND sounds abnormal you may find some relief with these kinds of additives. YMMV.

I like this video below in particular because the car owner partially discounts the loss of compression in one cylinder AFTER the "win" of having the engine flush raise the compression in the low cylinder. This is problem with these video: the tests are one-offs with no proven repeatability.


  1. Friction modifiers: most are so-called "snake oil" so avoid...
  2. Thickeners: just switch to a thicker grade of oil and save your money for future oil changes
  3. Solvent-based: good for unsticking varnished engine parts like lifters or piston rings. Keep in mind that solvents dilute the oil to a degree so it's best not to use them with a 5W-xx oil (dump the oil, add the solvent to 10W- or 15W- oil and then flush that oil after <follow the instructions>).

While the majority do not, some additives do have value but you must first understand what the problem is in order to apply the correct solution. For example, when my bus had been sitting for 6 years, the mechanic used some Rislone to get the hydraulic lifters working properly. He did this to avoid the need to remove all eight lifters to clean them.

There are umpteen DIY videos on YouTube demonstrating additives working and equally not working. See if you can guess the outcome of this video:

I can't criticize these products without doing my own tests; I'm just pointing out how a short video isn't going to be conclusive.

GM Engine Oil Supplement:

I managed to save a can of "GM EOS 1#992869 (500mL) for 6 & 8 Cylinder Engines" which was bought sometime in the 1980's to solve some continued lifter noises with my Westfalia after it had been sitting for six years.

GM EOS was primarily a ZDDP additive that was officially approved by GM for their engines. It's interesting to note that the appearance of this supplement predates the ZDDP scare. Reading from the can:

GM ENGINE OIL SUPPLEMENT is a multi-purpose additive concentrate designed to help...

#3 is interesting because SF oils were supposed to have boosted levels of ZDDP compared to SE oils. See API Classifications at the end of this article.


STICKING LIFTERS OR NOISY VALVE TRAIN: Add the contents to SF/CC engine oils at or between oil changes. If condition persists, consult your GM dealer.

NEW CAMSHAFTS AND LIFTERS: Dip base of valve lifters into this fluid. Pour remaining contents over camshaft lobes through lifter ports in engine blocks.

REPLACEMENT OR REBUILT ENGINES: Add contents to SF/CC engine oil with first crankcase filling and main in use for a least 1 600 km (1000 miles) of driving.

Manufacturer's Warnings:

But wait! There's more!

Here's an old 2002 FAQ from Mobil 1 that has been quoted many times over:

20. Can I use an engine "supplement" or engine oil treatment with Mobil Drive Clean Blend?

The use of an engine oil additive is not recommended, either by ExxonMobil or by virtually any vehicle manufacturer. In fact, it may void your new-car warranty.

AMSOIL makes a similar recommendation:

"Aftermarket oil additives are not recommended for use with AMSOIL synthetic motor oils."

Finally, VW's statement:

"If your Volkswagen is properly maintained, it is uneconomical to mix any type of additive with lubricating oils and transmission fluids."

All of this is largely due to the fact that there is simply no way for the manufacturers to keep with the the pour-in-additive market and verify what is safe and what is not.

The safest course of action is to choose the appropriate grade of synthetic oil (with sufficient levels of ZDDP) to begin with.

I've even read of several accounts demonstrating how the load bearing capacity of an oil can actually be lowered by an additive which is counter intuitive especially when that additive is extra ZDDP. Not convinced:

PTFE (Teflon) Based Additives:

Most oil additives advertise their "slipperyness" with the additional property that they will bond to metal and prevent wear even in the absense of engine oil. More often than not, Teflon (a Dupont trademark) is the key ingredient that keeps re-appearing decade after decade.

Read THE TRUTH ABOUT SLICK 50 by Fred Rau (x11.com) to read about PTFE (Teflon) oil additives. Some highlights:

  1. In a statement issued about ten years ago, DuPont's Fluoropolymers Division Product Specialist, J.F. Imbalzano said, "Teflon is not useful as an ingredient in oil additives or oils used for internal combustion engines."
  2. It should be noted that DuPont's official position on the use of PTFE in engine oils remains carefully aloof and noncommittal, for obvious legal reasons. DuPont states that though they sell PTFE to oil additive producers, they have "no proof of the validity of the additive makers' claims." They further state that they have "no knowledge of any advantage gained through the use of PTFE in engine oil."
  3. Remember, PTFE in oil additives is a suspended solid. Now think about why you have an oil filter on your engine. To remove suspended solids, right? Right. Therefore it would seem to follow that if your oil filter is doing its job, it will collect as much of the PTFE as possible, as quickly as possible. This can result in a clogged oil filter and decreased oil pressure throughout your engine.
  4. The Petrolon test report states, "There was a pressure drop across the oil filter resulting from possible clogging of small passageways." In addition, oil analysis showed that iron contamination doubled after using the treatment, indicating that engine wear didn't go down - it appeared to shoot up.

PTFE-based oil additives often work as designed: they make a lot of money for the manufacturer and leave your wallet extra clean.

See how PTFE reacts to heat:

The New Kid on the Block:

BestLine (grey bottle formula):

From their Material Safety Data Sheets (MSDS):

From the EPA's Substance Registry: CAS #9002-84-0 = Polytetrafluoroethylene (PTFE)

BestLine (black bottle formula):

What do I think? Watching these small engine tests that result in each motor successively seizing one after the other because THERE IS NO OIL IN THE SUMP isn't going to help anyone make an informed choice about the long term value of mixing any brand of additive with their automobile engine oil.

If the oil is wearing out and only a portion of the fluids in the crankcase are the pour-in-additives, are they going to be able to compensate for the worn out oil? I say they won't and based on the seized engine demonstrations, while they can outperform 100% oil, the engine still seizes so where's the miracle?

Engines need oil and all the testing videos on YouTube mainly use a machine that was adopted for testing additives by the additive companies (so called "Timken tests"). The oil companies engineer oils and run them through laboratory engines and road-going engines for thousands of hours or even million miles...

FTC vs. Oil Additives:

Every decade there seems to appear a new engine oil additive brand making incredible claims simply from pouring a bottle of their secret formula into your engine. Here are just a few of the more famous examples.

1. STP

2. Slick 50

3. Dura Lube

4. zMax

The FTC is the Federal Trade Commission and their mandate is "to protect consumers against unfair or deceptive acts or practices in commerce". All of the above products have become infamous for FTC judgements against their advertised claims.

Caveat emptor certainly applies here and why the french coined term "Coup de Thtre" so aptly applies.



01/02/21 - Moved from OilSelection.html into separate article