M1 15W-50 in 302

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I've tried thinner oils in my 1981 302 w/ 98k miles but they all foul the spark plugs.

I suspect "leakage" caused by worn rings or rings w/ clearances designed for thicker oil. Ford called for 10W-40 back in 1981.

THe use of xW-30 and xW-30 synthetics would foul the plugs in 30 days or more. I've replaced the valve stem seals already but the use of xW-30 would eventually cause a no start condition.

A few ppl suggested I tried synthetic 15W-50 in the motor year round.

Any ideas on this?
 
I am going to try M1 5W-50 or 15W-50 in my reconditioned 304.

Will be a few months till I try though
 
From what I understand the 302 uses pretty loose clearances, so this might be one rare case where a thick 50wt oil might work out pretty well. I say to go for it.
 
If that is the Chevy engine-I had one and it always used about a quart every 1500 miles. Naturally in those days I used a 40 wt. ('69 Camaro). Don't recall any plugs failing.
 
quote:

Originally posted by metroplex:
I've tried thinner oils in my 1981 302 w/ 98k miles but they all foul the spark plugs.

I suspect "leakage" caused by worn rings or rings w/ clearances designed for thicker oil. Ford called for 10W-40 back in 1981.

THe use of xW-30 and xW-30 synthetics would foul the plugs in 30 days or more. I've replaced the valve stem seals already but the use of xW-30 would eventually cause a no start condition.

A few ppl suggested I tried synthetic 15W-50 in the motor year round.

Any ideas on this?


I had a 1981 year 351 v-8 Ford once. The whole time I had it, I never had to look at the plugs. I just never had oil-related problems*. My oil? Castrol mineral single-grade HD-30.

[* The electrical problems were a killer though. G** ****ed Fords!!!!!! :)]
 
smile.gif


My 302 V8 doesn't use oil but it did blow out blue smoke once when I did a warm start (carb'd car, so you're supposed to hold the gas a little and crank) so I replaced the valve stem seals.

My definite guess is the ring clearance is causing the oil fouling problem w/ the plugs - again it doesn't do it with 10W-40 but it does it w/ 5w-30, 10W-30, and the synthetic xW-30s.
 
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