nutsy

this is my 3rd chrome bumper big block. I always used regular oil, rotella in my last one,
now have a 71 BB
this one was rebuilt about 2500 miles ago all stock except upgraded pistons whatever that means.
I know there are a hundred threads on here about which oil is better but my question is should I be using regular oil or full synthetic?
also is there a way to know whats in it now? I cant ask previous owner, he is no longer alive.
thanks for replies, Nutsy

C3 4ME

I don't know if there's a way to tell or not, but it's easy enough to do an oil change, so if wanted to make sure a specific kind of oil was in my car, that's exactly what I'd do.

Sayfoo

Lots of opinions out here. Seems like many of us have our preferences, not always based of science.
Someone saying that I've used XXX for ever and never had a failure, is mostly useless. There were some/a lot of cam failures years past that some people put on the low zinc oils. I this still a thing?
In my opinion, any name brand oil will be ok for general usage.
I now use Mobil 1 because I believe that synthetic is better than dino in every respect, and I stock it for my c6. Not necessarily need for general driving, but is probably helpful when pushing it and temps rise or with cold starts.

sug

I use a mineral oil with plenty of zinc in my 427.

DUB

Amsoil Z-rod 10W-30 is what I keep on the shelf and use for flat tappet engines.

Knowing that this engine is a flat tappet engine...it will be up to you if you care about having a oil that has the correct amount of ZDDP in it.

Then the next thing to consider that many people do not think about is how well the oil you choose is on the NOACK test. The Amsoil that I use and sell to my customers is very good on this test

Adding ZDDP in the oil of your choosing can be good or can turn really bad due to excessive amounts of ZDDP creates a corrosive condition. A which is why using 'break in oil' that is super high in ZDDP. all the time is NOT good for your engine. Sometimes MORE is not always better.

There is a sticky thread about oil where he tests oil and adds ZDDP to it and the results show that many times the oil does WORSE.

DUB

nix1981

I've been using Valvoline VR-1 10-30 and have been happy with it. It has higher zinc content. I think this may be the thread DUB is referring to:

https://www.corvetteforum.com/forums...ppet-oils.html

Rescue Rogers

It doesnt matter the type, make or anything if it isnt going to protect your old cam. First you need to find one that has very high ZDDP Zinc and phosphate levels high enough to protect that flat tappet cam. Then worry about if you want 10-30, 10 -40 or 15-50. You did right with the Rotella, its one way to go. I use Mobil one 15W50 from Walmart, its just under $25 bucks for a 5 quart jug. That beats OReilly at $10 a quart.

heres a list from Mobile One that gives the important info. You may have to chase down a list from other companies. The Rod Shop in my area carries the Amsoil but its very pricey.

https://mobiloil.com/~/media/amer/us...pecs-guide.pdf

The one I use is the 15w50 , third page, third from the bottom. This is what they say

15W‐50 phsphorous 1200, Zinc 1300, A Boosted, higher viscosity, advanced full synthetic formula designed for performance vehicles. For high HT/HS applications. Racing and Flat tappet applications

HeadsU.P.

This is easy to remember:

If it (engine) was born with mineral oil, let it die with mineral oil.
If it was born with synthetic, let it die with synthetic.

This goes for cars, trucks, boats, lawnmowers, snowblowers, tractors, generators, motorcycles, etc.

Just my opinion, but it does make sense.

CMD1

I also have a 1971 LS5, and I always have used Lucas Hot Rod and Classic motor oil 10w40 in it. Currently has 62,000 miles on it.
I also use it in my wife's 1977 Trans Am which she bought new way back in high school. Both have been trouble free as far as engine or cam wear goes.
Oil and beer are just alike......everyone has a favorite!
It can be a little hard to find locally for me, so I order it from Summit Racing in 5 quart jugs. I use a lot of Lucas products, never let me down.
Here is a link: https://lucasoil.com/products/hot-rod-high-performance

cv67

You cant tell the brand from an analysis Id bet just dump it and put your fav brand in it.
If its lasted 2500 it will probably be good indefinitely

nutsy

thanks for all the replies. very helpful and confusing.

HeadsU.P.

If you are at least 90% confused, then we did our job.

The forum members are pretty much burned out on this "best oil subject" so your best bet is to check out the oil sticky post at the top of the home page. There's just not enough dead horses around to beat on anymore.

nix1981

Haha! Sorry, that was funny to me.

F4Gary

I use the same VR-1 10w30 in my '72 LT-1. You can order it at O'Reillly Auto Parts. It's non-synthetic but works fine for my use.

REELAV8R

Synthetic vs conventional oil. Synthetic , true synthetic, is superior in every way vs conventional.

now if you plan on draining it every 2000 to 3000 miles and driving it in a pedestrian manner then paying for synthetic may be a bit of a waste of money. But even so it’s wear and flow characteristics are still superior to conventional oil.

Conventional multi viscosity oil is the lower weight oil with polymers added to get it to act like the higher viscosity rating. Those polymers shear with use and you end up with the lower viscosity over time.

synthetic oil is the higher viscosity rating oil base that has flow properties of the lower viscosity rating. So synthetic does not shear out of it’s viscosity rating with use. This alone allows for longer drain intervals, but also greater protection for the engine components with time vs conventional.

all this is irrespective of the additive package added to the oil.

if you need zinc, 1000 ppm min, then that would be a factor to consider when choosing an oil.

Mobil one 0W40 is a true synthetic with1000 ppm zinc, and it’s very affordable in 5 quart jugs at Walmart.

amsoil is undoubtably king in synthetic quality when it comes to oil, but at a price. So how good do you need?

DUB

Actually this is the sticky thread in the C3 tech performance section I was referring to:

.https://www.corvetteforum.com/forums...test-data.html


For those who want to look into the NOACK test...here are few on the graph below

NOACK Volatility Test (ASTM D-5800)





It appears that as long as the oil is under 15%...you should be fine.

https://www.mt.com/us/en/home/suppor...har_UC252.html

DUB

nutsy

I was doing a lot of reading on oil since I posted this to research some of the information on this tread. even though my engine was rebuilt 2500 miles ago there is a small oil leak. might just be pan gasket but anyway from what I read was if you have a small leak and want a big one put full synthetic oil in. that has got me thinking im going with regular oil.
also read that the ZDDP should be at least 1000 if I remember correctly and most oils that have it lowered it to 800.
then read that you can but an ZDDP additive but too much can do harm also.
as I said, very confusing, you guys did your job. but seriously thanks to all.
im going to see if I can find out the ZDDP amount in the rotella, I THINK!

oh DUB, just saw the link with the zink levels in it. very helpful, thanks

DUB

Hopefully you find what will work for you...and I can say that when I put in the Amsoil Z-rod oil in an engine that had some unknown type of oil in it and it had some small leaks....the engine generally does NOT purge oil like a crazy. Just saying. Because I work on so many engine that came with synthetic oil in them and they do not leak....and if they do...the leak is often times not that bad.....and if it is....I fix it.

DUB

Bikespace

Mobil-1 0w40 has been my choice, too.

stingr69

I use factory recommended Mobil 1 synthetic in my supercharged 2010 LS3. It works as intended.

I use Valvoline VR-1 conventional based racing oil in my old car engines. The silver bottle is the "street" version (with additives) of the racing oil. It has more zinc for the flat tappets and the additives that make it a good choice for typical street oil change intervals. 10W-30 is good for the bearing clearances I have. 20W-50 is better for looser bearing clearances. Need zinc for the tappets and conventional oil because I have had problems in the past with synthetics in old design car engines. It works as intended.