I am sure this has been hashed out here many times before and I don't want to start another oil thread but I be a newbie. Car I just purchased was rebuilt about 20k ago ('74 2.o) and the records show 15-40 weight has been used since rebuild and at all services. Now is this not a heavy diesel weight oil? I use this weight in my BMW 535i as recommended from factory, but a small air cooled VW mill using this heavy weight? Doesn't sound right to me. Clue me in please. Oh, engine is dual Weber's and a Web cam.
Thanks.

I use 20/50 in the 914s & the Bus (2.4/6).

Thanks Mark, I too use the 20-50 (Castrol) in my Alfa, 911 SC and Norton bike and was planning on using it in the 914.

15-40 is prolly Shell Rotella, which is a good oil designed for deisel engines, but fully compatable with a VW engine. Personally, I broke my engine in on Kendall 20-50 and switched to Mobil 1 15-50. Basically, anything 10-40 or heavier is going to be ok, although 20-50 is an ideal weight

I use 5w-30 and have plenty of pressure all around, actually when cold I almost peg my VDO pressure gauge, but I am running a new rebuild with a 30mm T1 pump.

New twist to my oil question. Called the PO engine builder/shop and asked why 15-40 weight oil used. He said they no longer use it, they now use 10-40. And not to use 20-50 Castrol as will cause VW motor to burn oil! Also do not use Pennzoil, Quaker State as well as Castrol! Go figure on this info from a Porsche/VW/Audi shop. Many answeres from many sources, all have their opionion. Leaves you wondering a bit doesn't it?

Woah you guys, you are all giving great advise, but look were the new guy lives. Around here, even in the winter, stick with 15-40. Either Delo400 or the Rotella. It is what I have used for years in my shop and many other local shops use it as well. Oil is driver habbit/climate related to a large degree. Don't put in 20/50, you will regret it. Just stick with what was being used. 15-40 is a good oil for air cooled engines.

DON'T switch to syn either. Stick with what you started with.

QUOTE (911914 @ Dec 27 2004, 09:33 PM)

15-40

10-30 for us CA guys ...

I've always used 10-40 in all my VW aircooled engines.

kendal straight 30 in winter, straight 50 in summer

QUOTE (type11969 @ Dec 28 2004, 05:12 AM)

I use 5w-30 and have plenty of pressure all around, actually when cold I almost peg my VDO pressure gauge, but I am running a new rebuild with a 30mm T1 pump.

Unless you live in an area where it's ALWAYS below freezing, 5w30 is WAY too thin. 20w50 is what the book says, and what we used at the dealer back when these cars were new. 5w30 is what you use in mid 90s cars, 0w30 in the newest ones. The Cap'n

QUOTE (SirAndy @ Dec 28 2004, 11:32 AM)

QUOTE (911914 @ Dec 27 2004, 09:33 PM) 15-40 10-30 for us CA guys ...

Wrong ...................... The Cap'n

how can you say it is too thin if I have plenty of oil pressure, even when the engine is hot on a 90 degree day? what are you basing this on? oil technology has come a long way since these cars were new and "the books" were written. Plus I have a gauge to monitor things. If I ran 20w-50, my cooler might just pop. 20w-50 worked great on my t1 with a worn 26mm pump on a hot day, but I can't imagine using it in this t4.

30mm pump pushes out much more flow than the stock pump, but the restrictions are the same, thus more pressure. Based on just that alone, I can get away with a thinner oil than recommended many years ago.

QUOTE (Cap'n Krusty @ Dec 28 2004, 01:06 PM)

QUOTE (SirAndy @ Dec 28 2004, 11:32 AM) 10-30 for us CA guys ... Wrong ...................... The Cap'n

has worked for me for 20+ years. never blew a T1 or T4 ...

Andy

i use 20/50 year round

Forget the weight, just make sure you use oil, period. That said, the reasons why newer cars use thinner oil is because the clearances are tighter. I use 10-30 in my Subaru, 15-50 in my 914. Works for me.

20w50 / W = Winter NOT Weight

use higher winter if your region is prone to very cold weather...but if it's a fairly new rebuilt engine any 40 weight oil is fine. I've gotten this question so often from damn customers at the FLAPS so much it's become annoying . Hmm.... W could stand for hmm...wax, water, or maybe just maybe weight, b/c oil can't possibly freeze cuz it's not water...(o umm sarcasm mode initiated )

My understanding has always been that a

10w30

will flow like a 10 weight when the oil is cold and then once the oil is up to temp it will flow like a 30 weight. (same for 15w40 or 20w50 etc etc)

So would seem to me you would want a 10 or a 5 to get the oil flowing at start up. That is when the wear is worse and you need to get the oil moving as quickly as possible. Then when the engine warms up the oil will act like as 30 or 40 or what ever is needed in your engine.

To me it would sound like you would need a 10w30 or maybe a 10w40. You would not want anything over a 10 for the cold side, then you would want a 30 or 40 for the hot side depending upon your clearances and the wear in your engine.

Just my two cents.....

tom...

yeah, my understanding is the same as yours Tom. I figure that as long as you don't have a pressure problem, use a thinner oil to get it where it needs to be sooner at startup, instead of just relying on whatever residual film is on the parts from the last time the engine was run. And with the oil tech of today, the oil can have a stable broader range than when these cars were made, so you can have you cake and eat it too with a thin oil at start up, and a thicker once warm.

Take a look at the passages in the case that the oil has to go through and pour out some 20w50 on a cold day. If that doesn't convince you that a thinner oil might be better . . . Well you certainly won't have a pressure problem during cold starting, but ask yourself if you really think that oil is going to make it anywhere quickly.

Just my .02.

So what about the "newer car" spec 0-40 syn oils (Mobile 1)?

The problem I have with mobil one in a t1 or a t4 is the cost. If your engine leaks, you're wasting more moolah than if you were running dino oil. Even more of a problem is if you have a lot of blow by or an engine breather system that isn't adequately filtered, your oil will get contaminated and you will not be able to take advantge of the extended oil change intervals that make synthetics more cost effective. I run mobil one in my daily driver and love it though (5w-30). It pours like water at any temp, and I change it every 5k so it is only a little more expensive (if at all) than a dino change every 3k. Synthetics are less prone to thermal breakdown which is a good thing in our hotter running air cooled engines. And they are probably more stable for cars that sit for extended amounts of time. So it is really a trade off I guess.

Once I get the PCV system sorted out on my (now) leak free t4, I'll probably go synthetic. Should be interesting to see if there are any noticeable pressure or temp changes.

-Chris

According to Bruce Anderson in Tech notes II, this is Porsche's latest recommendations for 356, 912, 914-4, 914-6 and 911 through 1973.
For summer or warm climates:
SAE 20W-50
SAE 20W-40
SAE 40
For winter or in cold climates:
SAE 15W-40
SAE 10W-30

Bruce also recommends not using synthetic oil for motors that came from the factory without it.
The oil properties are diferent and the motor will leak oil.

larger number = thicker oil right?
50= THICK
10= Thin?

The higher the number the thicker the oil.
I remember reading that Castrol has foaming problems and some people don't recommend it.
In Bruce Anderson's Porsche 911 Performance handbook he lists the following oils and does not list Castrol:
Kendal, Quaker state, Valvoline and Pennzoil or Mobile One for synthetic.
I'm running 15-50 Mobile One in my 3.2 and I'm planning on switching to regular 15W-40 because of new oil leaks.
Can anyone recommend a good oil in this weight?
How much more is Kendal versus Quaker State?
I will have to see what's available at Costco.

I seem to remember Jake stating that he had problems with quaker state.

Freezing Factor of Motor Oil

QUOTE (Steve @ Dec 29 2004, 09:41 AM)

According to Bruce Anderson in Tech notes II, this is Porsche's latest recommendations for 356, 912, 914-4, 914-6 and 911 through 1973.

Is there a link to these Porsche recommendations? I would like to see those for myself.

QUOTE (Tom73 @ Dec 29 2004, 03:25 PM)

QUOTE (Steve @ Dec 29 2004, 09:41 AM) According to Bruce Anderson in Tech notes II, this is Porsche's latest recommendations for 356, 912, 914-4, 914-6 and 911 through 1973. Is there a link to these Porsche recommendations? I would like to see those for myself.

Not that I know of.
You could email Bruce Anderson and ask him where he got the info from.
I got the info out of Technical Notes II dated May 2001
It comes free with a subscription to Excellence
Its on page 76 and its labeled Oil for older Porsches.
Its says that Porsche changed there recommendations about 10 years ago for older cars.
Which means this information is dated around 1991.

You can always post the question to Excellence to see if anything has changed.