Synthetic oil is good for air-cool engine

[sagaboy]

It took 25KM of mix highway and street driving on 10/30wt dino oil for the oil to barely reach 170F

After switching to BP Synthetic 10/40wt oil it only took 12KM for the oil to reach 180F and with higher/faster idling engine speed plus more power/torque. (BP Synthetic was on half price sale and which was what prompt me to gave it a try).

From my observation, it is obvious that Synthetic oil have the unique ability to absorb heat from moving parts of the engine or that heat from the engine moving parts are easily transferred the Synthetic oil which translate to a cooler engine with less wear and tear.

In my opinion, I can conclude that higher price Synthetic oil is worth using if we want our air-cool/oil-cool engine to have lest wear and tear. I shall never go back to using dino oil.

[craigvwdude]

Synthetics is all i use!

[Jim Ed]

It took 25KM of mix highway and street driving on 10/30wt dino oil for the oil to barely reach 170F

After switching to BP Synthetic 10/40wt oil it only took 12KM for the oil to reach 180F and with higher/faster idling engine speed plus more power/torque. (BP Synthetic was on half price sale and which was what prompt me to gave it a try).

From my observation, it is obvious that Synthetic oil have the unique ability to absorb heat from moving parts of the engine or that heat from the engine moving parts are easily transferred the Synthetic oil which translate to a cooler engine with less wear and tear.

In my opinion, I can conclude that higher price Synthetic oil is worth using if we want our air-cool/oil-cool engine to have lest wear and tear. I shall never go back to using dino oil.

How do you know that it is not absorbing heat as well or as fast and that is the reason your oil temp only went up to 180F?
Do you have a cylinder head temp gauge too?

[neil68]

I only run full synthetic in my Beetle.

My belief is that oil's purpose in an ACVW is mostly as a lubricant, and air is what keeps the engine cool enough to operate properly (that and proper tuning, of course). Synthetic is simply a superior lubricant, therefore less friction, lower engine temps, less engine wear, easier start-ups, etc.

Yes, the oil goes through a cooler, so that has a role in cooling off the warm oil, as well. I actually don't worry too much about head temps...because they vary so much depending on driving habits (hills, acceleration, etc).

Do different oils absorb heat at different levels? It doesn't really matter...

[sagaboy]

Jim Ed said "How do you know that it is not absorbing heat as well or as fast and that is the reason your oil temp only went up to 180F? Do you have a cylinder head temp gauge too?"

I drive the same rout to work every day for the past 20 years and 9 years with the VW since I got it and have taken note of the oil temperature all along. The only reason I can think of in comparison with the dino oil temperature before and after switching over to synthetic oil and that is... before--dino oil needs 25KM to reach 180F and synthetic need 12KM--that indicates that synthetic oil is superior in absorbing heat from all parts of the engine and that alone means therefore less friction, lower engine temps, less engine wear, easier start-ups, etc.

Basically, the VW is oil cool and with some air cooling the heads/fins--a big part of the heat from the heads are absorbed by the oil splashing on the pistons therefore in my opinion the oil is very important to a VW engine.

[MinamiKotaro]

Basically, the VW is oil cool and with some air cooling the heads/fins

Really? Remove your fan belt and head down the interstate, see how long heat transfer through the oil keeps your engine from melting down.

[Jim Ed]

Most of the arguments that I have read about using synthetic oil in aircooled engines sum up with it is OK to use it but, it costs more and has to be changed at the same interval where the interval equals 3000 miles with a full flow filter and 1000 miles with no filter or a bypass filter.

[Piledriver]

Most of the arguments that I have read about using synthetic oil in aircooled engines sum up with it is OK to use it but, it costs more and has to be changed at the same interval where the interval equals 3000 miles with a full flow filter and 1000 miles with no filter or a bypass filter.

If you put a sandseal in with a proper PCV system you could probably double that, possibly triple with the right oil
(still assuming full flow and deep sump)

True synthetics deal with high temperatures better than conventional oil, so they seem a reasonable choice, much as full flow filtration.

[neil68]

I change my synthetic once per year and I do run a full-flow Berg remote filter set-up with a non-bypass Geers filter. I've changed camshafts several times (for Friday-night drag racing) and the bearings, lifters, etc, all look brand new each time.

I agree that non-synthetic is fine in a stock Beetle...after all, we all managed just fine with dino oil for decades. Some prefer to spend a little extra money on quality synthetic oil.

For a stocker, 2.5 litres of synthetic oil is not that expensive (<$20), but it's all relative of course...how much do you value your Beetle engine and how long would you like it to last with cold start-ups, etc?

[Jim Ed]

This Fall I plan to switch over to Royal Purple 10 W 30 since, it has the right additives for flat tappet engines.

[ainokea]

Agreed, synthetic oil is superior to dino oil, but, if oil and filtre changes are done every month, need it or not, I think that the use of synthetic is not necessary. All of the air cooled engines that I've built and owned over the the last 40 years, got an oil filter change once a month, and I average only 500 to 700 miles a month, in temperatures averaging 80 to 90 degs. My latest engine is a 1955cc, running dual 44's, no deep sump, just the normal doghouse cooler with an oil pump with a spin on filter. I just keep the oil clean. This is simple maintenance and it has worked well for me.

Thanks for letting me spout off,
Ainokea

[rockerarm]

Heat is not the only enemy our air-cooled engines battle. Wear, whether it is pre-mature or takes a long time to show its results, to me, is the most important issue. I have been on a different web-site (bobistheoilguy.com) and have learned that UOA, or used oil analasys, probably is the most determining factor in decideing if an oil is doing its job. The camshaft/lifter and the valve adjust screw/valve tip relationships are more important than a few degrees in oil temperture drop. I'm sure I will raise a few off their chairs and get some comments.

I agree, synthetic oil is a marvelous product. I believe the main reasons to run a synthetic oil is:
1- Required by the MFG for warranty purposes.
2- Required if you are utilizing a turbo, whether its gas or diesel.
3- One wants to increase their oil change intervals.
4- Approved by the camshaft grinder or engine builder.
5- Has a suffiecient additive package to allow critical parts to survive.

My $.02, Bill

[Piledriver]

You won't get much argument here.

There are some epic threads here covering what oils are/are NOT suitable for flat tappet engines, dino and synthetic.
The main lesson--- What's suitable is a constantly moving target, as the non commercial formulations can be changed at any time.

Short; Rotella-T 5W-40 synthetic (g3) and Valvoline VR-1 oils are available almost anywhere.
The Rotella can even be had at Wal-Mart.

Diesel rated oils are about the only oils ~universally available that have enough zddp.
The Chevron Low Emission LE400 does NOT BTW, avoid at all costs, like Castrol GTX.

I'd love to recommend Brad Penn and Swepco etc but you simply cannot grab a bottle at the gas station if needed.
(I have a local retailer for BP, YMMV, severely)

Just found out GM et. al are requiring a new non-API standards called "dexos/dexos2" or somesuch for 2011 models.
I know nothing about these oils. yet.

If things go per usual that's all Wal-Mart will be selling in 6 months, as everyone knows wal-mart customers all drive 2011 models..

[aussiebug]

I am pleased to see Piledriver and Rockerarm have introduced more than the simple Dino/synthetic question here.

It's a lot bigger question than "are synthetic oils better?"

ALL oils have improved out of sight in the last 40 or more years.

The problem is that we are trying to compare MODERN oils with the needs of our OLD engines. Modern oils are developed for modern cars, not 40 year old ones. Engines design has improved a lot in that time, and oil technology is trying to keep up.

So lets have a look at it.

Lubrication

VW used to recommend single weight oils which had to be changed with different ambient temperature ranges. Then in about 1975, when multigrades became reliable, they started recommended mulitgrades. They always stated in the Owner's Manuals that any good brand HD (that's High Detergent, not Heavy Duty as some would think) oil was OK, and this made sense as the car was sold all over the world so good oil anywhere would do the job - the engine was not too fussy about the brand so long as it was a good oil. Almost all 4-stroke engine oils back then had large amounts of ZDDP added - up to about 1400PPM.

Oil is supposed to prevent metal to metal contact in an engine - maintain a film of oil between all moving parts. But our flat tappet engines need more than just oil - they need an anti scuff agent to stop metal to metal contact in those high pressure areas like the flat tappets. To do this, oil engineers have long used an additive called ZDDP (a Zinc/Phosphorus compound). As luck would have it - this compound is also an excellent antioxidant, so it also helps cope with the corrosive combustion by-products that get into the oil.

ZDDP is sacrificial.
1. It works as an anti-scuff agent by decomposing with the heat of microscopic metal/metal contact and coats the contact area with Zinc, which eventually wears off and so the process repeates. This zinc coating reduces the wear on cams and tappets, but does not eleminate it completely.
2. It chemically combines with combustion by-products to produce less damaging chemicals in the oil.

So you need enough of the stuff in the oil to last until you change the oil again.

Modern engines need less or none because they usually have roller tappets, and the engine computers used these days control the combustion process much better than a carburettor or mechanical FI ever could, reducing the amount of combustion by-products significantly.

Cooling

Overcooling and undercooling are equally damaging. Ovecooling increases the viscosity of the oil and the engine is always designed to work with a set range of viscosities - obviously an over-thick oil will not flow as well as one which is "just right". Under cooling will increase the oil temp and reduce the viscosity, risking more metal/metal contact.

Another factor not often known about is that for ZDDP to work, the oil MUST be hot - I had a long discussion with a 30 year oil engineer at Castrol Australia who stated that ZDDP will not get to a high enough temperature at the metal/metal contact point to decompose and do it's job, unless the general oil temp is above 80c (176f).

Claims like "I use synthetic oil because the oil temp goes way down" might be completely anti-productive.

Summary

Oil manufacturers are reducing the maount of ZDDP in oils as it posions catalytic converters. Manufacturers are designing engines with roller tappets so they do not need so much (or any) ZDDP in the oil.

Many modern oils do not have much if any ZDDP, which our old engines still need.

Synthetic v Dino oils.

It doesn't really matter that much in terms of lubrication in general - both will do the job. They will both also carry engine heat to the oil cooler much the same. And both have changed there formulations a lot in recent years, so either could be right or wrong for our old engines. But I do not know of any synthetic oils which have significant levels of ZDDP (let me know if there are some).

The Castrol Engineer I spoke to said that despite the out-of-sight improvment in oil technology in recent years, our old engines will last longer if they have some ZDDP in the additive package. In Australia Castrol Edge Sport oils have a higher level of ZDDP than most - above 800PPM. But oil formulations around the world do differ, so we as owners, must determine if the MODERN oils available locally to us meet the requirement of our OLD engines. In many cases, certain oils are only available in certain countries - Royal Purple and Brad Penn in the USA, Duckhams in the UK, Penrite in Australia, and so on. And even the "common" oils like Castrol, Shell, and BP use different formulations in different countries.

So we have to consider the WHOLE deal - lubrication, viscosity, additive package - it's not enough to say "it runs cooler with this particular oil", or "I change my oil every 1000 miles to it doesn't matter what I use".

It's a little harder for us these days, because oil technoilogy has moved on from our old engine designs...we have to get a little more choosy ourselves, and to do that, we need enough knowledge to make the right choices.

I guess the average aircooled VW owner has to be smarter than the average bear

[Piledriver]

Well said.

The following list is "what I can find locally", US centric and not definitive.
Subject to change without notice, eat your vegetables.
I include Brad Penn only as I can buy it down the street from where I work by the case.
YMMV.

Synthetics are tough... Not many "off any shelf' suitable for older cars. Most that are ==diesel oils.
In the US:
Rotella-T synthetic runs around 1300ish PPM zinc/phos.(can be bought ~anywhere)
Mobil1 Turbo-Diesel/Truck (AKA Delvac1 in a different bottle) is also way up there (see bitog for NOA/UOAs), the "commercial" AKA diesel rated oils change formulations "harder" due to the ~$500K recertification from just about any formula change.
I'd tun the TDT/Delvac1 if i could find it, the 3 huge truck stops up the road never heard of it, and Wal-Mart stopped carrying the TDT.

Esp. note that Mobils "Truck/SUV" oil is NOT the same as the "Turbo-Diesel-Truck" and is liquid death at ~800ppm zinc.
("Liquid Death" came from from Jake Raby back when he was doing oil testing, I forget what oil he was actually referring to)

Diesel rated oils also have hugemungous detergent packages (that's a scientific term) that COULD cause the ZDDP fils not to form as easily and to break down easier--- but as the big diesels are harder on their lifters and injector pumps than anything we have, I suspect the oil companies figured out how much detergent was "too much".
The Mobil1 15W50 red stripe is allegedly also ~1400ppm, but I keep hearing about issues... again, see an oil centric site like bitog for more info if you want to run that tar. See http://www.lnengineering.com/oil.html for an excellent primer on oils for high performance aircooled engines.

After being a believer for 20+ years I stopped using any Castrol product when i figured out GTX 20W50 turns into water in about 1K miles in an ACVW.
(Charles' testing had it around SAE25 so I wasn't crazy)
Note: USA Castrol GTX oils are ~800ppm zinc/phos and are not suitable for flat tappet equipped engines (per Castrol).
That means YOU, Mr/Ms ACVW owner. Ignore the spiffy commercials.

Non synthetic:
Delo400 (NOT the LE "low emissions" version, its ~800ppm) and Mobil DELVAC are ~1300 ppm zinc.phos as well.
The 15W-40 Rotella in the white bottle is marginal at ~1100ppm zinc/phos
The Shell HD single grades were still 1400ppm last time I looked.
Brad Penn GT1 is a synthetic blend, 1400ppm.
Valvoline VR1 (available at most FLAPS) 1400ppm all grades.
The NSL VR1 versions have ~no detergent packages and even higher ZDDP and may be considered race day oils...
May not be suitable for DD use or especially storage.
Swepco makes some great oil if you can find it, same for RP and AMSOIL I'm sure, and there are other specialty oils sold that are specifically for flat tappet engines... Harley dealers will merrily sell you 20W50 with plenty of ZDDP in it. (The non HD brand stuff is even reasonably priced)

The main thing to remember (and it got Brad Penn in some hot water---)
All these oil companies make NORMAL "new car" oils with low ZDDP too...
Just because it says Brad Penn on the bottle does NOT make it automagically safe to use.

You must be 100% aware of exactly what you are feeding your antique engine at all times.