Kendall GT-1 Competition 20W-50

[jimaushea]

I asked a highly respected local Porsche service facility, specializing in air-cooled 911s and 356s, what motor oil to use in my '88 3.2 Carrera. Without hesitation, the mechanics and mgt all recommended the subject conventional/ mineral-based oil, partly because of the high zinc content and thathe fact my car still has solid lifters. But the forum here, though there are a couple highly-positive mentions of this oil seems to have many more more positve reviews of other oils such as Brad Penn, Mobil 1, Valvoline Valvoline VR-1 etc., most of which, if not all, are synthetic. So I'm confused!

[winders]

There is no reason other than nostalgia to run conventional motor oils in '88 3.2L Carrera. If it is a street car, Mobil 1 15w-50 is perfect. Synthetic oils are better than conventional oils in every way.

Check out this link to see the higher levels of phosphorus and zinc as needed by engines like the air-cooled Mexger engine in your car:

https://www.mobil.com/lubricants/-/media/project/wep/mobil/mobil-row-us-1/pdf/mobil-1-engine-oils-product-guide-sheet--may-2022.pdf

[Schulisco]

Based on my personal experience I recommend to follow the long year experience of the mechanics from the highly respected workshop and to use exact that kind of oil what they recommend. This was also the recommendendation from Porsche.
And yes, to be honest and this is also part of the truth - Porsche delivered 911's factory filled with a Shell TMO in the late 80ies, which was a synthetic oil 5W40 afaik.
But now we're talking of 40 year old engines with several 100'000s miles, some still unopened since. The wear is undoubtly and the seals won't seal as they did when new. Mineral oils have bigger molecules, and they let the rubber based gum seals swell which helps sealing the engine. If've read many reports of 911 with oil leaks which became tight again by switching from modern synthetic oils back to the old fashioned mineral oils. Of course - if the seals of the engine are really bad, then you won't get it sealed again without engine overhaul.
Also we're talking about climate change and increased ambient temperatures so that a 40 oil may reach it's limits more often, so that it makes sense to use a 50 or 60 oil depending where you're living and what's the purpose of the car is (rollin' around and normal street use, engaged drives on countryside or race track).

And yes - modern synthetic oils are way better in all disciplines against any (old fashioned) mineral oil. No question. But - those engines were designed and constructed 50years ago for those oils and fuels available at that time (and a bit later)....so I'll exactly usw them in my SC.

The later models as the 964 and 993 engines were getting slightly modern, so they had to use more and more modern oils as well.

I use a 20W50 as well with best experiences. Good pressures, almost no more oil leaks underneath the car. The workshop filled a mondern fully synthetic 10W60 in it: I had oil leaks on to the heat exchangers with heavy smell that I thought the engine burns....

Thomas

[Ralph3.]

Recommended and used by a local air cooled mechanic who is active on this forum.

[winders]

Oh my God….I ran Mobil 1 15w-50 in a 3.2 Carrera engine for 10 years and never had a problem with it. So did MANY of my friends. Jerry Woods told me back in the mid ‘90’s that Mobil 1 15w-50 was excellent for my 3.2 engine.

[pmax]

Here ...

https://www.porsche.com/usa/accessoriesandservices/classic/genuineparts/producthighlights/motoroil/



I believe Porsche might know something about these engines.

[winders]

From that same site:

[kach22i]

About 10 years ago I used Kendall GT-1, 20W-50 for a couple of years, not perhaps the Kendall "GT-1 Competition 20W-50" now being discussed.

My friend an I both heard a bit more throatier engine sound, which in turn aided the perception of more power - especially torque.

All non-sense perhaps, but I really liked that oil and was disappointed that I could no longer get it locally.

I looked into special ordering it and also looked into it's ratings, pain in the butt to order and lower than expected scores/ratings so I just stopped using it.

Maybe if I can find these red bottles in the spring I will give it another try.

As far as sealing up the engine, I will never trust a full synthetic again.

What sealed up my (engine for a while) was driving the car for about six hours straight (Dino oil), not a drop of oil under the car for over a month after that.

[walt]

I ran this Kendall oil a few years back and always thought my engine temperature was running a few degrees hotter. Have since switched back to Valvoline racing.

[Bill Verburg]

Originally Posted by pmax

Here ...

https://www.porsche.com/usa/accessoriesandservices/classic/genuineparts/producthighlights/motoroil/



I believe Porsche might know something about these engines.

Believe what you want but porsche is all about marketing, they are selling you their version of a product but they don't disclose the constituents of that product.

They used to recommend M10w-40 before they brought their own product to market.

In case you are unaware the oil issue is all about the level of ZDDP, specifically Potassium and Zinc levels, which need to be in the range 1200 to 1600 for our older air cooled engines, their recommended 0w-40 contains 1000/1100 ppm P/Zn, below the optimum levels

M1 15w-40 is 1200/1300 right at the lower end but has been proven satisfactory for countless users over countless years. More is not better Mobil's racing oils 20w-50(not suitable for street use due to short drain intervals) is 1600/1750 ppm, That is a cap.

Any oil in the range 1200 to 1750 will be acceptable as long as it has the right weight spec., synthetics are prefered but not absolutely necessary.


Bottom line,

Why would you purchase a product w/o knowing for sure that it has the right ingredients?

[Ralph3.]

I buy by the case from Petroleum Services Company, free shipping.

[pmax]

Originally Posted by kach22i

...
As far as sealing up the engine, I will never trust a full synthetic again.

What sealed up my (engine for a while) was driving the car for about six hours straight (Dino oil), not a drop of oil under the car for over a month after that.

This is on the 77 I assume, which synthetic oil was that ?

Interestingly as posted above, Porsche also recommends mineral on everything older than the 3.0

[pmax]

Originally Posted by Bill Verburg

Believe what you want but porsche is all about marketing, they are selling you their version of a product but they don't disclose the constituents of that product.

With regards to the syn vs dino question, Porsche has no such reason to prefer one over the other given both products are offered for sale so it is safe to say there's a good technical reason for the recommendations they made, something to do with the seals and tolerance of the Mg engines perhaps favor a more varied molecular mix ... who knows, I'm no tribologist. Anyone ?

[Bill Verburg]

Originally Posted by pmax

With regards to the syn vs dino question, Porsche has no such reason to prefer one over the other given both products are offered for sale so it is safe to say there's a good technical reason for the recommendations they made, something to do with the seals and tolerance of the Mg engines perhaps favor a more varied molecular mix ... who knows, I'm no tribologist. Anyone ?

seal swelling is a canard still floating around from the '60s, initial syns were in fact not reacting w/ seals like dino, that was quickly remedied.

50 odd years later it's still no issue

The advantage of syn wrt dinio is at the temperature extremes where syn is better, no you don't need the extra protection(most n/a anyway) but it's still nice to have a little more latitude wrt to engine protection when it's really hot or really cold.

[winders]

In stop and go traffic, the head temps get way up there....synthetic oil is your friend then!

[pmax]

Originally Posted by Bill Verburg

seal swelling is a canard still floating around from the '60s, initial syns were in fact not reacting w/ seals like dino, that was quickly remedied.

50 odd years later it's still no issue

On the other hand, I will take it as fact, given there's absolutely no reason to suspect otherwise, that those reporting leaks after switching to syn are telling the truth as are the cases reported in this very thread. So is it the original seal reaching end of service or the oil or the incompatibility between the two as Porsche has stated ? And yet, given no manufacturer divulges what additives they have in their oil and what has changed over the decades, it is stated without any technical basis that today's formulation, and that itself is a moving platform as the composition is regularly tweaked, is all good. And then there's the fact that these engines are constantly being rebuilt in aggregrate, and somewhat amusingly some done because of leaks caused by the wrong oil, as they age so naturally the new seals are probably compatible with the new oils and the presumbly leak free result contributes to the self confirmation bias that it must be the bad original seals, not the incompatible oil as Porsche states.

[Bill Verburg]

Originally Posted by pmax

On the other hand, I will take it as fact, given there's absolutely no reason to suspect otherwise, that those reporting leaks after switching to syn are telling the truth as are the cases reported in this very thread.

observatiuoanal bias, for every one balminf syf for leaks there are 100s w/ no issue

Originally Posted by pmax

.... And yet, given no manufacturer divulges what additives they have in their oil

true only in the broadest sense, the thing we need to be picky about is ZDDP and weight as defined by P and ZN ppm and the SAE spec

Mobil amounga few other publishes this info yearly( see Scotts link above) oil

analysis can also provide this info, the last Blackstone I saw on Porsche 10w-60 was
940/1007 right is line w/ their old 0w-40 rec of 1000/1100, obviously they are ok w./ these levels but the preponderance of feeling in the field is that it is a tad low. I'd as sume save a few bucks , get as good or better oil packages a little more ZDDP and a more appropriate weight( w/ 20w- 50 my new 993 lifters take a bit of time to fully pump up, 60w might exacerbate that)

oil seems to be like religion or politics to some, despite all the preponderance of real evidence some will always refuse to believe differently,

I was a happy w/ dino 20w 50 till the 90s when I switched to M1 and never looked back,

anecdotally I have seen syn but w/ the wrong weight and ZDDP content ruin a perfectly good late 964 engine in a very short time span. That's not evidence either.

[PeteKz]

Originally Posted by winders

In stop and go traffic, the head temps get way up there....synthetic oil is your friend then!

Ditto. Oil temp seems to get at least as hot during stop and go summer traffic as running on a track. When I see the needle going north of 240 in those conditions, I'm glad I have synthetic oil.

[Antomero]

This is what I use… and love it! My engine run great and cool, under all driving conditions

[stownsen914]

Please move this thread to PARF lol