Looking for Oil recommendations...
 

First for my Cobra Replica with a 1995 Mustang 302.

Second for my 1968 Corvette (327) that is currently running 20-50. Looking for a good brand but think I want to keep that weight...


Thanks!

Valvoline-20-50VR1 racing oil this also depends on the mileage of the engine. Castrol is outstanding too.

Thanks. The 68' Vette has about 120k on it.

Lots of threads on this subject here, Brad penn 20-50 works for me. Also Joe Gibbs racing oil 20-50 works great but a bit more expensive. Both have lots of ZDDP and can't be used on a car with a catalytic converter.

Lucas Racing Only 20w-50 High Zinc. Good price from Summit. I get my FL1AHP filter from them also.

Would you use the 20-50 in the 302 also?!?

He11 no!!!!!

As someone said you do not want to use ZDDP in a fuel injected engine, as it kills O2 sensors.

50 weight oil is for engines that were built with loose tolerances, in full out racing type usage.

Look in your manual. I would bet Chevy called for 10-40 in the 68 327.

I think Ford called for 10-30 in the 95 5.0.

Do as you want. I wouldn't run 50W in any factory built engine, unless the manual expressly called for it.

The type, weight, and brand you use depends on what you intend to do with the car.

Synthetic oils have two major advantages: Heat resistance and long drain intervals. Most cars will easily go 12,000 miles between oil changes. And synthetic oils will handle 250*+ for hours at a time without a break down.

A true synthetic oil starts with a PAO base stock, not dead dinos. AFAIK, there are only 4 PAO oils on the market: Royal Purple, Redline, Amsoil, and Schaffer.

All other oils sold as a synthetic are really not. Due to a legal trick of marketing, they can sell a dino oil as a synthetic if it has been processed enough to meet certain performance requirements. Doesn't make it a bad oil. But it does make it a deceptive marketing plan (IMO) and not necessarily a good value.

Oil gets hot from extended rpm's, like road course or open road racing. For street driving, drag racing, or autocross, Dino oil won't get hot enough to break down.

Dino oil work just fine for the vast percentage of vehicles on the road. I use Royal Purple in my air cooled Harley and racing Cobra. UOA supports this. Everything else gets dino oil. Mobile1 would not hold up for 4,500 miles in my air cooled Harley.

ZDDP was reduced in gas and diesel motor oils because it can clog up the cats. Doesn't hurt the O2 sensors, though. If you don't have cats, I suggest a decent additive. I use Comp Cams break in additive.

Viscosity is another big point of confusion. And here's where you really have to pick carefully. Viscosity of a petroleum product is most affected by temperature. It's usually measured at 40*C, and that gives you the basic viscosity of the product. For example, a 40 wt oil will have a viscosity of 40 at 40*C. But it will have a different viscosity at different temps.

The first number (ie: 5W) tells you that it will have a viscosity of 5 when it's cold, usually measured at 0*C. The second number (ie:40) tells you that it will pour like a 40wt that's been heated to 100*C. At that temperature, it will NOT have a viscosity of 40.

For the first number, you want it to be very low, so that the engine will start easier and the oil will pump quickly to the bearings when cold. The colder the oil is, the thinner the oil should be. Most engines should do well with 0wt.

The second number is the operating viscosity. You need enough viscosity to maintain good oil pressure. More than that puts a strain on engine components and causes drag. That makes the engine less efficient, builds more heat, costs you power and mileage. Look at the recommendation for a lot of new cars - 0W-20.

20W-50 is NOT the correct oil for the vast majority of engines.

Some race engine builder say that a 40wt is needed for valve train stability in racing conditions. But most say that a 30wt is perfect. Some NASCAR teams are using a straight 0wt oil.

As far as oil changes go, that again depends on the vehicle, use, and type of oil. Let the UOA be your guide. My diesel pick up gets an oil change every 15,000 miles. The air cooled Harley every 8,000.

If you use a dino oil, change it every spring. Over the cold winter months parrafins and waxes can congeal and form sludge.

Nice write up Bob!!!

I changed the oil not long ago.. .in my spf.. 351w...(crate) and put in what I had sitting in my garage..(as my other car lives on it and it was handy)
Valv 20/50 synth.

351 DOES NOT like it... it smokes on start up... and at idle...

will go back to conventional for this application.

Look at SWEPCO oils , gear lube and greases ..... a well kept "secret" . One of the few oils/lubes approved by Porsche , Audi and Mercedes .

The problem is not that it's a semi-synthetic. The problem is that it's a 20W-50 oil. Your engine will live a long and happy life on 5W-30 dino oil.

And if you're driving a Porsche or VW, that's fine. Also, keep in mind that companies often pay manufacturers so they can be the "Official Oil" for the brand.

OK so if 20/50 is the wrong oil what is the correct oil for a 408 stroker with 4300 miles. It's only had 20/50 since new.

THANKS for the advice on the oil I put in.
..
Even though it is 60+ here today.. it will be 20 again by Christmas.. so the oil change will have to wait..........

I hate you warm weather owners..........(ok HATE is a strong word.....; but well you know.....)..

The quickest way to determine correct viscosity is with bearing clearance information. Without it is an interative process. With respect to small block based engines anything between 55 psig - 60 psig at 6k rpm is good and anything above 25 psig at idle. That being said the risk of too heavy of an oil is your oil pump relieve valve always is relieving most are set at 60 psig from the factory. So if you are below 60 psig you are getting all the flow if you are pegged at 60 psig you most likely are bypassing.

In the end as long as you are not racing anything will work!!!!!!!!

So is 20-50 okay for a 45 year old Chevy 327 then? I had heard that as an engine ages, with niles, it is better to go with a "thicker oil" to make up for the wear...

Thank you Bob Cowan for the very nice and simple write up. I now understand a few things a little more - although I am still changing the oil on my Harley every 2,500 miles. I know it is over kill but just makes me feel good to change it every year.
:)

Any good 5W-30 dino oil will work just fine. I happen to like Castrol GTX, but there are other good ones on the market. If you drive more than about 10K miles a year, a true synthetic will allow you to change the oil less often.

Maybe. It depends on the condition of the engine. If the engine 45 years old, but not driven much and is well maintained, then - once again - a good 5W-30 will keep the engine running strong and efficiently.

You need enough viscosity to maintain oil pressure and no more

Sometime you just have to do whatever helps you sleep at night. :)

Sometime you just have to do whatever helps you sleep at night. :)
That's the bottomline.

As far as oils go, Joe Gibbs for me but some of the others are good as well, comes down to personal preference/experience. If Keith Craft swears by Joe Gibbs then that's all I need to know. It's going in a DART aluminum 427w race block. I'm using it in my BMW K1200S sportbike, 11.5:1 cr, runs like a champ.

What helps me sleep is doing what is right! ;-)

It has 20-50. Old owner had the car for 35+ years and swears by it so maybe I'll stick with that...