Thread: What kind of oil for a high mileage engine?

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Dont know if you guys can pass on some links on oil info. I have a 350 sbc with about 200,000+ miles on it, I know its getting time for a rebuild). It calls for 5-30 on the valve cover but theres got to be some better for the looser clearances of a high mileage engine. Dont know if it makes a huge difference but the engine see a lot of idle time. Thanks

I've heard folks say good things about Valvoline's hi mileage oil....never have tried it myself, still on Mobil 1 in the Bonneville's 3.8 at 146,000 miles....

You probably need something heavier like 10-40 or 20-50. The first function of oil is to provide a squishy boundary between parts and secondarily under high pressure when the viscosity breaks down there needs to be something like ZDP. You could use a small amount of an additive like:

http://www.sfrcorp.com/product/sfr-1...-oil-fortifier

in 10-40 or 20-50. Another option is to switch to Diesel 15-40. Here is a good study sponsored by Amsoil about heavy duty conditions:

http://www.synzilla.com/testimonials...use_hauler.htm

Ultimately cost is a factor and Amsoil is very expensive, but maybe some other diesel oil like Rotella T 15-40 might be cost effective. I am running the 15-40 in my Sunfire with 89,000 miles. I tend to favor higher W oil but there is a limit in increased heating and some increase in friction but surely you can move up to 10-40. I was really impressed by the No. 1 rank of Amsoil in the "four ball test" which I am familiar with from employment by Socony Mobil many years ago when I had a summer job synthesizing ZDP derivatives (there are many possible ZDP compounds, depending on the hydrocarbon groups attached to the P part of the molecule).

Don Shillady
Retired Scientist/teen rodder

I'm with Don; I like 20w-50 to hold them old heaps together.

I prefer straight 30 in warm weather in my older engines, 15-40 in the fresher ones. You live in Texas, how cold does it ever get there?

I think I would go with a diesel CL4 oil higher sulfur that has been removed for the new vehicles ED

My 85 Suburban has 345,000 and I use Quaker State straight 30W. I swapped to straight 30W at 200,000 miles. Good oil pressure. My front and rear seals leak so I am on a continuous feed and bleed. Just go ever 5000 miles for an oil change. Gotta love them sbc.

Originally Posted by BigTruckDriver

Dont know if you guys can pass on some links on oil info. I have a 350 sbc with about 200,000+ miles on it, I know its getting time for a rebuild). It calls for 5-30 on the valve cover but theres got to be some better for the looser clearances of a high mileage engine. Dont know if it makes a huge difference but the engine see a lot of idle time. Thanks

Hi there,
If Valvoline stateside has it 25/60 is a brew for this situation.
If your MAIN bearings are noisy in a cold start then Pennsoil
40/70 might be the last offering...Good luck,
Skyeking....

For many Years I have used Castrol GTX 20W-50 . Lately in the Cooler weather I use 15w40 Shell Rotella Truck Oil . We use 15W-40 all year Long in are Trucks at work many have over 500K Miles .

Here is a Good Oil Tech Info Link http://micapeak.com/info/oiled.html

check out

www.bobistheoilguy.com

I would not run 20W-50 unless you drive it pretty hard all the time. Higher viscosity leads to higher friction and temperatures which reduces viscosity and promotes break down. Chevy recommends 5W-30 for their ZZ502. Also depends somewhat on the clearances the bearings are set-up with. Higher clearance applications will favor the use of higher vidcosity oil in general.

Kitz

I wouldn't be too hasty changing to a diesel oil in an older engine. The high detergent content is going to free up all the crud that's built up over the years, that just ain't going to be good for the old bearings when it washes through the system.

I wouldn't be too hasty changing to a diesel oil in an older engine. The high detergent content is going to free up all the crud that's built up over the years, that just ain't going to be good for the old bearings when it washes through the system.

Think I'm gonna agree on that. If the oil you have been using has carried you to 200,000 with no problems, why mess with what is working ?

If you've been using 5W-30 and don't add more then a quart or two in 5-6000 miles, I probably wouldn't change a thing except maybe go to 10W-30/40, but stay with the same brand, especially if you idle lots. 200K+ with today's engines and the electronic/computer management systems is not as much wear and tear as the carbed and point distributed engines of years past.