Im getting about 10 psi at idle and 25-30 on the highway (oil pressure). The engine (302 V8) either has 108k miles or 208k, not sure which exactly. Next oil change Id like to switch to a diff. weigth oil to see If i can get the pressure up some. Right now Im running Motorcraft 10w-30. What would be a good weight to run next change?

Thanks

 

The rule of 10 psi per 1000rpm is a good one, and unless your racing that engine I think the pressures you have are ok. Putting heavier oil in it will only add pressure when it is cold. I myself would leave well enough alone. Kotzy

 

I agree also with the pressures,, sound ok to me. But if you really want to feel better, you could switch to 10w40 or even 20w50 given you are in a warm area of the country for the 20w50. Jim

 

Finally, someone who gets it. Well said Kotzy. Also, AmericanMade, when you put heavier oil in the 302, your gas milegage will suffer. Unless you are very happy with the great fuel milegage you get, heavier oil (especially during cold start and warm-up cycle) will make the 302 use more gasoline. Your $$ at the pump, nobody elses.

I would stick to a quality 10w30, your oil pressure specs, and mileage on the engine are very much in the acceptable range.

Good luck.

 

Sometimes we forget & directly associate "oil pressure", with "oil flow" for a given viscosity, past a given restriction!!!!

When oil is cold & it's more viscous & resistant to flow, the pressure to move a "given volume" through a restriction rises. when the oil is warmed up to operating temp & it's viscosity is lower than when cold, it's easier to pump & requires "less" pressure to move the same volume through the same restriction.

SO, by increasing the oils warm viscosity number, the pressure will rise, but the "volume" of oil past that same restriction at the same pressure & temp, won't!!!!

SO, putting in a more viscous oil, to see a higher oil pressure on the meter, doesn't mean more oil volume past the bearings. It just means the pump is having to work harder to move the more viscous oil!!!

I think i'm of the same mind as kotzy. If the engine isn't knocking when warmed up, 10W-30 should be fine.

My 78 3.3L I6 is specified for 10W-30, or 10W-40 & with 10W-30, runs about 15 psi at idle, when warmed up & about 45 psi when crusing. When cold, the cruise oil pressure is about 55 psi.
It has 135K miles on it, so I'd guess with your psi, you probably have 200K+ miles on yours.

Now if the engine is noisy with 10W-30 & you wanted more oil flow to the bearings, maybe a higher flow rate oil pump would be worth considering?????

If it's still noisy when warmed up & you want to try & quiet it down some, without an overhaul, maybe try 5W-40 in the winter & or 10W-40, depending on the weather temp range, where you live.

Just some thoughts to ponder.

 

If your bearings are a little on the "loose" side then a thicker oil can and will help get more to the top. Go with the 10w-40 and see what happens. I bet you're mileage won't suffer enough to notice.

 

If it were my truck, I would run 10w40. In fact, my truck (below) was getting 15 and 35 psi on 30 weight so I switched to 10w40 and now get 18 and 44 psi. I like it since spec is 40-60 at 2000 rpm hot for my engine.

If you want to try the thicker oil now, you can drain off 2 quarts and dump in two quarts 20w50. That will give you about 10w40.

When hot on the freeway run it under load for about 20 seconds (maybe up a grade) then suddenly let off the gas while observing the oil pressure gauge. The more the oil pressure jumps when you let off the gas, the looser the bottom end is. Two or three psi not bad but more could be trouble. Thicker oil will help fill that gap and gives you a higher HTHS viscosity.

Another thing, maybe the oil pump relief valve is leaky (weak spring maybe). I suspect that is my problem. Also oil pumps wear more as they get the oil pre filter. It is possible a new oil pump would help oil pressure, and I don't mean a high volume pump, but exactly a stock pump, but new. But then again, it might not help.

Regardless, you are above the magic number of 10 psi per 1000 rpm, so even if you stay with 10w30 you should be fine, but being in TX you might as well throw in a quart of 20w50 or straight 40 or something like that to thicken that 10w30 a bit. There is some dispute on that 10 psi per 1000 rpm rule regarding whether it really applies to the first 1000 rpm. Some say you should have maybe 15 or 20 psi at idle and then add 10 psi per increased 1000 rpm from there.

Every official Ford oil pressure spec i have seen is listed only hot at road speed (usually 2000 or 2500 rpm) with no idle spec.

 

Ed,

You've got no proof that the fuel mileage will suffer...you offer no proof at all. But I, sir, have in my possession years of records of fuel consumption to show there is VERY LITTLE DIFFERENCE between the use, even in winter, of an oil like a 15w-40 and a 10w-30. I have the records of the 1988 Crown Victoria (302 using 15w-40) as compared to the 1997 using 10W-30 from the same manufacturer, with the same driver, over the same course. Years of comparisons and virtually NO difference, even considering the differences between the two cars. I have years of record keeping to back me up, Ed. What do you have?

Americanmadeford: When the engine blows, who is gonna pay for the replacement? Right, you are. Go with your gut and do the right thing. That heftier oils will protect you better in the Texas heat coming upon you real soon. Go with what is proven year after year.

I wrecked a perfectly good sweet singing 327 using "salad oil"-remanufactured light weight engine oil "RATED" heavy duty (it said 30W-30 on it. Seven miles with that stuff trashed that engine....cam lobes missing, lifters worn through the bottom, others cupped badly. Go with your gut, use the heavier oils for your own protection.

 

I agree with you.

 

Actually, his oil pressure spec (302 V8) is 40 to 60 psi at 2000 rpm hot (just looked it up), and his exhibited oil pressure is well below that range. Why does Ford specify this range? And why does Ford bother to specify the 460 V8 as 40 to 65 at 2000 rpm? Seems like the difference is insignificant. They must have a reason. I would say something is worn, be it the relief valve spring, the oil pump, or the bearings (he can test these with the procedure I stated above). If it is the bearings, then I'd think one would want a thicker oil (not necessarily a lot thicker) to take up the slack.

 

MPG is meaningless if I lose this engine, and Im not a gambler.


Thanks for the tip Paul. Ill run that "test" next chance I get.

So, most seem to be in agreement what 10w-40 is a good oil to run? Im trying some Lucas Oil Stabilizer right now, but will deff. try 10w40 next oil change.


Thanks for the replies yall!

 

don't shoot.
some of you know i'm having issues with a 92 Galant (yes, yes, not a Ford...indulge me) and a nasty ticking (Hydraulic Valve Lifter) and generally run 5W-30.
she's spec'd for everything from 5W-20 to 20W-50.
I had the 10W-40 in my trunk, vice the 10W-30 i bought for a little test i'm running (compression, ARX and photos), so she got the 40...and ticks even worse! I can only imagine my MPG plummeting....
I bought 5W-20 tonight, wondering if i should throw that in instead????
thoughts?
thanks.

 

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I'm not saying if say, you are getting a peak 15 MPG, that by using a thicker oil, it will drop to 9-10 MPG. However, it will drop, and that peak 15MPG will be less. LESS MPG = fuel guage getting to EMPTY, SOONER rather than later. That is a fact. Compared to the 10w30 oil, you'll lose MPG, not gain MPG. Hence, everything I said, is true. You'll go less miles, fill up or stop for fuel sooner. If that is fine with AmericanMade (as I stated) then he can use the thicker oil, knowing this.

You seem to think, I feel a engine will not start or run with a thicker oil, or fuel mileage will be night and day difference. I knew that. Again, if his MPG is 15 max. (a made up number) he will not achieve 16.6 MPG using a higher viscosity oil.

Ed

 

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I never saw an oil that said 30W-30 on the quart or jug container. Perhaps that was your problem, a cheap oil (I noticed you didn't mention the brand) that was not very good. Hence your 327 went south, and that is a shame. Maybe you'll pay more attention next time, and not buy something that says 30w30. That 30W probably pumped like taffy at the local County Fair, when cold, even in the summer time.

What proof do I have? 1973 Dodge Charger SE. 440 CI 4BBL 727 auto, AC (ice cold) dual exhaust, 2 1/2" w/ "H" pipe. Drove Charger from NE Ohio to northern California. Used 10w30 Castrol GTX oil. 65-75MPH cruising speed, with AC blowing ice cold. Plenty, repeat plenty, of passing power. Never ran hot, or overheated, when climbing mountain passes, Interstate 80 in Wyoming, Utah, Nevada and northern California. (I did gear trans down into "2" however, on steep climbs) Purchased Charger in Jan. 1978, second owner, I was 19 years old. Still own car. 53000+ orig miles now. I can reach in and turn the key, and that big 440 will fire and rumble after that brief Mopar starter whine, made famous in the 60s and 70s. I never needed your heavy syrup /tar oils in my engines. I wonder why?

1987 Aerostar Van 3.0V6 146K+. Purchased van at 17,000 miles. Use 5w30 oil, mostly brand name dino, but I have used 5w30 Royal Purple, 5w30 Mobil 1. Van does not use a drop of oil between changes. AC used, ice cold, in bumper to bumper traffic after a 35-40 mile freeway drive in 105-110 northern California summer weather. 5w30 oil. Van runs normal. Never overheats, garage floor is spotless.

I can give you 4-5 more examples, wifes cars and others I've owned. I have not used a 10w40 oil since 1977, and have had no oil related engine problems / failures with those "demon" lightweight salad engine oils.

Ed

 

I see in muddyaxles post the oil which was 30w/30 was a remanufactured oil. The engine failed because of an improperly blended lubricating oil, not its viscosity.



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