Best oil viscosity for our engines

[Alexander C.]

Re: Best oil viscosity for our engines

I'm running Redline 10w40, original engine with a rebuild ~1965 and only about 8K miles since rebuild.

[Ronald L.]

Re: Best oil viscosity for our engines

Do I dare jump in - yes!

There is one oil company mentioned here, that has a 300k mile guarantee using synthetic. Guess what, last year you had to start that before 75K, now the other day I passed the SAME bottles and you have to start 'on the program' by 125k.....WHY????? It is real simple and fits nicely with Einstein quantum mechanics,...you have the change the oil very 3000 miles. Does it matter its synthetic? No Way, the theory of relativity was easier by the way.

Think of heat like the oil in your frying pan...hot is one thing, too hot and it starts to break down in the presence of oxygen.

Larry follow as Peter has done, that VR1 synthetic is good stuff and provides good viscosity under hot climates. For those that are worried it is too thick, blend it down with some 5w30 and know that it is approximate 3 5w30 and 3 20w50 will get you pretty close to a 15w40 mix. Or, this time of year, change the oil again to the lower viscosity oil, afterall its only money and that in itself is relative.

BTW - the new engines, all aluminum and very precisely machined are running 20 weight oils, less rolling resistance, but don't buy those 10000 and up oil change intervals...unless you just prefer to buy a new motor at 100k miles.

[Duke W.]

Re: Best oil viscosity for our engines

Duke - put Valvoline VR1 Racing oil in my 71 LT-1 because the web site said it had zddp/phosperous of .014/.13 which I now see your article says is ok but at outer bounds and not necessary to be that high. Also, it is 20w-50 synthetic oil which now makes me think weight was not a smart thing based on this thread for my engine either.
I also read that the racing oil might(?) have also been a bad choice because it does have the right detergents/additives/whatever but thought(likely incorrectly) that only mattered if you drove the car all the time as opposed to weekend toy like a 71.

Thoughts?

Thanks

Pete

My thoughts.

Well, first, there is no direct measurement for ZDDP - only P and Zn.

The Web site said... Did you ever read the article in the Corvette Restorer on engine oil? Did you ever look at the Web resources and source material that were referenced in the article?

All the answers are there including how to select viscosity.

There appears to be two different Valvoline racing oils. One is designed especially for real racing engines where the oil is changed after every race, and may not be API rated. The other... It's very confusing.

It's not a concern to me because the only Valvoline oil I would use would be their 15W-40 CJ-4.

Any street driven car that has oil sitting in the crankcase for a period of months or years, and is not torn down every few operating hours, regardless of how often it is driven, needs an oil with a full dose of detergents and dispersants.

Road engines are NOT racing engines, no matter what. They have a completely different set of operating conditions and different lubrication requirements.

Duke

[John F.]

Re: Best oil viscosity for our engines

I think we all need another life if we are going to keep worrying about oil in our cars. Change the oil and filter every 2000-3000 miles and worry about more important things! Drive the darn things.
John F

[Frederick W.]

Re: Best oil viscosity for our engines

Sure, we're obsessive about things like originality, but this obsession with engine oil is pathological. It's noteworthy that none of these discussions arise from anything originally posted here. It's always when someone posts a link to another Web site with some seeping pile of b....t.

NCRS members should know better. They have the benefit of a better education on this issue - both through the Corvette Restorer and the TDB, which is why I am confounded by the continuing surfacing here of the old myths, misinformation, and junk science that polute most automotive discussions on the Web.

Duke

I guess some of us are just slow learners. (In my defense, I've only been an NCRS member since earlier this year, so maybe it'll just take me a little longer to catch up).

The TDB is an authoritative place to go for accurate information, thus my original post. Thanks to all who have commented.

I would be interested in your Restorer article, Duke.

Fred

[Peter M.]

Re: Best oil viscosity for our engines

Ok thanks for input

Pete

[Peter M.]

Re: Best oil viscosity for our engines

John - you may be right but trying to follow this and having read Duke's article, it appears that rule of changing every 2k or 3k, as in old days, is not good for our motors since th eoild is missing a chemical that is bad for valvetrain. Hence the interest in making sure we are using right one?

Thanks

Pete

[Duke W.]

Re: Best oil viscosity for our engines

Reprinted Corvette Restorer engine oil article - starts on page 3.

http://www.westcoastwillys.com/WCW_Sept08_small.pdf

Duke

[Domenic T.]

Re: Best oil viscosity for our engines

Perhaps you can expand on your statement.

Duke

Duke,
If that was for me, what I meant was that what a manufacturer recomended back in those days would only be better now with the improvements of the oil today.

When you look at the intervals the manufacturer recomends on oil changes for basically the same engines today it shows that something changed. The metal basically is the same in the blocks as it was back then but the time between changes has been expanded. We went from 2,000 between changes and more than doubled it today because of the improvments they made with oil.

Therfore when said that one should follow what the manufacturer recomended back then was good enough (which I totally agree with) then it ought to be that much better today with the improvements oils have made.

Thats what I was adding in agreement with what you said.

DOM

[Duke W.]

Re: Best oil viscosity for our engines

Okay. Base stocks used to blend modern oils have better oxidation resistance, today, which is one reason why oil change intervals can be extended.

Additive packages are "tuned" to modern engines, and modern "roller everything" spark ignition engines don't need as much anti-wear additive, but the diesel manufacturers have resisted significant reduction in anti-wear additive, which is why C-catergory oils are best for vintage engines.

My recommendation for collector car oil change intervals using C-category oil that are driven a few hundred to a few thousand miles per year is once per year and just prior to storage if the car is stored over the winter.

If mileage is less than 500 in a year, I think it's okay to go two years.

Manufacturer's oil change recommendations are based on cars in daily use that accumulate annual mileage in the thousands, but they always have a time limit, too, and it's usually one year.

Duke

[Christopher R.]

Re: Best oil viscosity for our engines

BTW - the new engines, all aluminum and very precisely machined are running 20 weight oils, less rolling resistance, but don't buy those 10000 and up oil change intervals...unless you just prefer to buy a new motor at 100k miles.

Funny you should mention this. I just bought a new car with an aluminum engine. The recommended oil is a 20-something or other. I thought to my self that it sounded awfully light-weight.

Is the more modern thinking re oil weight in new cars is that the new engines are so good and the new oil is so good that we can get away with light-weight oil. Or, that we use light-weight oil so that we can advertise high fuel efficiency ratings and the warranty will expire before the harm becomes evident?

[Doug F.]

Re: Best oil viscosity for our engines

Therfore when said that one should follow what the manufacturer recomended back then was good enough (which I totally agree with) then it ought to be that much better today with the improvements oils have made.

I agree that the oil is likely better and I think a lot of it has to do with the detergent and surfactant additive packages. I am not so sure the additive packages back in the day were necessarily tailored for the engine. I don't know how much anti wear additives were added in the 50's and early 60's. Growing up, it seemed remarkable to see 100,000 miles on an engine. Nowadays the village idiot and drive the car and easily get 100,000 miles on an engine. Then again, maybe the shorter engine life we saw growing up was a product of our economic condition. As kids, we and our friends were typically poor and bought used (abused?) cars. Seems like someone always had an engine that had blown. And in many cases, teenagers are not too far removed from the village idiot.

Having said that, I think a larger component of the extended oil change intervals on newer cars is the fuel injection, tighter machining tolerances, computer management, PCV systems, unleaded fuel etc. Improvements in these areas have optimized fuel ratios and decreased contaminants such as fuel, oxygen, water vapor and combustion gases in the oil system. Reduction of the contaminants leads to less dilution and degradation of the lubricant.
Doug