The importance of choosing the correct oil weight.

[Wildthings]

So sulfur in molecular form just acts like elemental sulfur??? Just like carbon in CO2 just acts like elemental carbon??? hardly. An element combined in a molecule can have very different properties than when in a pure form. The difference in sulfur found in ZDDP is going be be very different from the sulfur found in an extreme pressure additive, especially a traditional one. There is a reason ZDDP is added to motor oil and for the most part reactive sulfur EP lubricants are not. One doesn't cause excessive acid to buildup in the oil and the other does.

[raygreenwood]

[DeathBySnuSnu]

I have to agree with Ray for the most part. I have to deal with ratings and such to pick oils for the machinery I build.
But.
If you change it a lot....as in "I dont have an oil filter" lot. Then it is most likely you will not see any appreciable build up.

I certainly would not choose diesel oil for this app. But you are probably ok......ish...

Try running 10w30 to 10w40 oil to get a feel for what it needs in weight.

[oprn]

My former engine machinist (big block Mopar racer in his spare time) told me "run a medium quality 30 wt'ish oil and change it often." when I asked him these same question years ago.

I think it still applies.

[EVfun]

Thanks OPRN. Why does every discussion about motor oil have to turn into a shit-show? Last I checked this is the oil WEIGHT thread, but it has degraded into another what type to use thread, with the usual acrimonious dick wagging unrelated to viscosity.

The correct viscosity to use has a lot to do with internal clearances and materials used, and complicated by an aircooled design that may or may not have a thermostat, and uses an oil cooling system based on pressure over actual oil temperatures. Those building engines have some knowledge of the insides that gives them particularly important input. I can understand why they avoid the fight an oil thread turns into; however, I would really like to hear what weight(s) to use, and when, and why, from those supporting their work and our hobby.
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[oprn]

I truly believe oil weights are a regional thing just like clothing. The further south you go it seems the heavier the recommendation. Here in our part no one carries anything heavier than 15w40 diesel oil in quantities large enough to do an oil change. You have to special order it as they don't want to get stuck with a dead end product on the shelf no one uses in anything.

Last year I was having trouble with the oil pump not holding a prime and the pressure dropping suddenly on my new to me, well used 1600. Someone (in the south naturally) told me it was because a VW engine NEEDS 20w50 oil. Well I have never in 40 years of driving VWs used it but what the heck... Had to go to 3 local oil venders to find 3 liters of the stuff and it was almost double the price of normal oil.

Worth a try but no, it did not fix the issue.

So up here we wear sweaters and jackets in the summer sometimes and use much lighter oil.

[Wildthings]

[Onceler]

I know these oil discussions always are controversial, but I enjoy reading them. It's good mental exercise. I had an old s10 that I never changed the oil, just added when it got a quart low, but it had 300k on it up to that point so I couldn't justify spending money on maintenance. Now if it was a vehicle I needed to rely on it would've gotten regular oil and filter changes, but then again I always buy the house brand shit. It's more fun for me to rebuild a engine than to stress about changing oil, lol
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1972 Karmann Ghia

[Wildthings]

[Frodge]

I have a question about oil weight, regardless of brand. Gene Berg says to run 10w30 unless the temp is 80-85 most of the time, which he would then run or consider to run 10w40. I live in the nyc area and basically drive most of my miles when it’s warmer. But in this time like early spring and fall it can go into the 50s, but the summer can be really hot, like 80 and above. So I kind of fall in both camps. I have 10w40 in it right now, and as an example, it’s like 90 degrees today, and tomorrow will be even hotter. It’s a stock 1600 single port engine. What is best to run?

[Wildthings]

[Frodge]

Thanks for the reply. I appreciate it. Will I do harm by having 10w40 in the summer? Asking because I changed it 2 weeks ago.

[Wildthings]

[Frodge]

I have a question about weight and seals. Is there a substantial difference between 10w30 and 10w40 and the effect it has on engine seals? Will one or the other potentially create more leaks etc. I’ve read some people say using the heavier oil started leaks and some say going to a thinner oil started leaks? Any credence to this?

[Xevin]

[modok]

IMO 10-30 is normal.
So, start there and go one way or another based on what your doing that isn't normal.
If you run extra hot and/or extra loose go thicker. 10-40, 15-40

Want to run in the COLD maybe be go to the 5-30or 0-30, but, in most cases I would not. These are mainly used in new cars for the sake of fuel economy, and cold starts. Vw engines warm up pretty fast.
you want to reduce wear get a full flow oil filter, get the thermostat working, get REAL air filters, then we will start worrying about wear at start up.

Synthetic oil or thinner oil sometimes will leak more, but, it isn't a big difference. If it's leaking too much fix the problem. If it's leaking a little don't sweat it(pun), it's a VW. magnesium does in some cases, literally sweat oil. the few seals on a VW should be silicone, and be compatible with any kind of oil.

[Wildthings]

[EverettB]

[oprn]

We have a Jetta TDI that uses 5W40 wt and has a tendency to leak a small puddle from the oil cooler seals when started cold at -20 or lower. Once it warms up it stops.

[Frodge]