What Oil To Use - one opinion- Warning- read heavy

[Wentzel]

Hi guys, I am planning to do an oil change the weekend and was wondering what brand and weight of oil you trust and use in your aircooled engine. I have been using Shell Helix (20W50) for some time but think I should try something like 15W40 maybe shell also. What have you found to work good and what shouldn't I try?

[Edmond]

Im going to run Castrol Magnetec 15W40 in my new engine since it has a 30mm oil pump and dont want it to have excessive oil pressure but I've always run 20W50 in my baja both Castrol GTX and Shell Helix and never had a problem

[Pine]

I've always used Shell Rotella SAE40

[hitlers revenge]

I also only use SAE40

[jmvv]

Consider the age of the original engine design.

It was designed when our grandfathers were just a dirty thought in our great-grandfathers' minds.

The modern oils (15W40 etc) are formulated with the modern engines in mind. These engines run much tighter tolerances than our beloved aircooled engines.

With Castrol GTX 20W50, I have found that the oil pressure at 2000 RPM drops from about 3 bar to about 2 bar as soon as the oil temperature exceeds 50 degrees Celsius.
(I have both an oil pressure and oil temperature gauge fitted)

According to a technical boffin at Castrol, that is about the temperature when the additive pack in the oil cause a change to the viscosity of the oil.

Driving into a hailstorm earlier this year, I noticed that the oil pressure picked up from 1.5 bar to about 3 bar as soon as the oil temperature dropped below 50 degrees Celsius. (This was after a sustained 120 kph - with the oil temperature a 110 degrees Celsius)

When our aircooled engines were originall designed, there were no multigrade oils, so a monograde will work fine.

I believe that, if you are serious about protecting your engine, use any synthetic 20W50 oil.

[Tony Z]

http://www.aircooledvwsa.co.za/viewtopic.php?f=4&t=6181

[Sambabus]

Castrol Magnatec for my bus aswell.

[Dirk]

Mobil 20W50. The one in the gold containers.

I've also tried SHELL 15W40, the one in the blue containers.

Both served me well. But I now stick exclusively with MOBIL, as the SHELL one reaches running temp very quickly and seems to break down faster.

Personally, I don't trust Castrol. I've been informed by parties I consder trustworthy, that the quality controll procedures are not what they used to be.

[4agedub]

Shell helix 15w40

[retrovan]

Hi Guys,
This is only my opinion on a subject that will provoke a lot of comment from different viewed guys here on the forum.

Disclaimer;- This post is My opinion ONLY, not a dig at anybody, and not a finger in the eye of others with different opinions.

Terms and Conditions;- This post is to give you info, that you may want to GOOGLE, to find all the technical terms, and explanations for your self, so if you use this info, which ever way you go, its on your head.

My opinion, in layman’s terms;- What oil to use has been a bar fight topic for many years. When you look at old Service Manuals, it states that you should use SAE 30 or something like that, BUT when you look at a newer Car Service manual, it tells you to use a 20W40 or something like that.
Old school will tell you that the car maker is right, and should you be allowed to use anything else, it would be in their Manual.
New school will tell you that they have learned from their mistakes, and that technology has changed.
Who is right….. You decide, here is some info to help you.

When oil started being used in machines, the engineers found that if you flood the part, the oil will get in where it needs to go. It worked.
Then some clever Dick came and fitter oil pipes to guide the oil where it should go, and then flood the part. Worked better, and saved oil.
Dick then worked out that if you pumped the oil in to the wear places, the machine would last a lot longer.

Now in lab conditions, at a set temperature, and you know the gap between parts, you can work out what thickness oil you need to fill this gap.

If your gap is too small, the oil will not go in there, and the part will seize. As oil can not reach the full surfaces, and heat up, run dry, and melt.

Now you can do a few things,
One, pump at a higher pressure, this will force the surfaces open, run ok, but when oil is thinner, till start knocking, and destroy it self.
Two, Increase the gap, the same problem as point one.
Three, decrease the thickness of the oil, But if you leave it like that when the gap grows, you will have the same problem. Not if you modify the oil to have the same pressure ability as an thicker oil, thus, it will fill the gap nicely, and carry on working.

If you put a MONO thickness oil in you car, saying that the clearances are still correct, as per the Service Book, lets say SAE 30. The oil is the correct thickness to fill the engineered gap when on running temperature. As this is where the engine will be most of its life. BUT when you start it up when cold, the oil is too thick, the gap too small and the oil cannot get to cover the parts fully. THIS is the time you do the most damage to you engine, and why they say do not thrash the engine till it is hot. Or you will damage it.

If the engine gets old, the gap is bigger, and the SAE 30 will not fill the gap any more, and seize, so now you have to go to a thicker oil. But now you have the problem again when cold.

So Technology has made the Multigrade oil, which, when cold, is the right thickness, so NO damage on start up, and has the pressure ability of a thick oil when hot. (this they do with additives ) so no damage when hot.

(Additives;- Things they put in like wetting agents, to make it stick to parts, polymers, to give better lubrication at higher temperature that will not flow away from parts when you need it)

Now the most important thing, is that you get the correct heat/thickness range for your area and driving style.

In South Africa, it never gets very cold, so it will not be necessary to go lower then SAE 20, and even with a bad engine SAE 50 will be fine, so most cars will be happy with a oil like 20W50 Never go to a 5W20 or 10W 30 as it will not get that cold.

Now remember that these additives break down and get used up, as well as the petrol that by-passes the rings, dilute the oil, so you MUST change the oil on your car service Manuals intervals, as they know how far it dilute, the older the engine the more frequent the oil changes.

TWIDT (The Way I Do Things)

Herman

[calooker]

I think what is far more important for our aircooleds to know what is in the oil more than anything else. Old fossil oils had the right mix for out flat tapets but with the onset of catalitic converters & emission controls a lot of what was in the fossil oil (what our air cooled flat tappet motors need) is almost non existent.

Oil has changed a lot in the last 10/12 years or so, not due to the oil manufacturers but more because of the motor manufacturers. In some countries like US, Germany, it is law and oil needs to adhear to strict regulations & standards, this causing oil companies to fall in line. This brings about change, and what is actually in oil ? I have been looking at oil diffrently, I also said oil is oil, but have learnt that this is not true.

After having 2 not so stock engines give me problems due to rapidly worn out followers, promted me to start looking for answers. Btw I allways use the same formula in parts and assembly. A buddy who does engine building for a living has been having issues too.

Our old engines were happy will fossil oils with lots of zink, phosphorous (ZDDP) and no detergents, todays oils have reduced levels of ZDDP this is done to protect catalitic converters and CO sensors as the zink kills them off, in doing so, a lot of the lubrication properties needed for our old engines is lost. This is true as our engine need the zinc in the 2 areas of much sress, the cam & followers, and this also applies to many other vintage cars that run a similar setup.
In my search I found that ZDDP levels in Castrol GTX has dropped from around 1300ppm (ppm - parts per million) to around 800ppm, and from what I got to find out, ideal levels should be around the 1200ppm in our fossil motors.
So to make a long story short one should be using oils with a ZDDP level of around 1200ppm.
There are adittives out there that can be mixed in to boost the ZDDP levels, I have never been a fan of adatives of any kind so have decided that a change of oil in my motors especialy anything more than a stock engine.
By the looks of it, oils that are formulated purely for racing, as they don't have to worry about cat. converters is the way to go, as well as some other off the shelf stuff.
This is what I have found:
Mobil 1 15w50 full synthetic (1300 ppm ZDDP) this one is especialy formulated for flat tappet engines
Casrtol synthetic 20w50 (1200 ppm ZDDP)
Shell Rottela 15w40 (1200 ppm ZDDP)
Shell Rottela 5w40 full synthetic (1300 ppm ZDDP)

There are quite a few others but they are not all for sale here in SA, these mentioned above are rather pricey and the racing stuff even more.

The initial run in of a motor is where the engine is under the most stess and where the right oil can mean the diff. between it having a good life or a premature end.

[fig]

I use Shell Rimula SAE40; it's a heavy duty oil formulated for diesel engines, which experience the same kinds of heat and pressures as our ACVWs.

I don't know what its ZDDP levels are, but thatnks for explaining that Rui. I had previously been warned about ZDDP levels and cam follower failures, but I had no idea where I'd find my ZDDP levels.

[kts customs]

i used mobil one

[bugspray]

I bought 3 bottles of extra virgin olive oil for R100 at Food lovers market yesterday :/

[Golfmad]

I only use Shell Helix HX5 15W40 - but then again, I dont have an aircooled engine