Hi everyone... I have a 79 f150 4x4 short-bed w/400 4bbl that my boyfriend is going to do an oil-change on, "with me learning how to do it myself, in the process" My question is this... What is the best oil to put in my truck & why ? Also, what should the oil-psi be running, & at what mph ? I live in San Jose, California. A mild climate , w/night- time lows in the 50's & daytime highs 80's to 90's . Thanks !!!

 

In my '77 w/351M (only difference between 351M & 400 is crankshaft and pistons), I use a dual rated (diesel/gasoline) oil in 15W40. Shell Rotella, Chevron Delo, Mobil Delvac and Motorcraft Super Duty are all good quality oils. The diesel rated oils contain a little higher level of zinc and phosphorous antiwear additives which help decrease/prevent wear on the flat tappet comshaft.

And I stick with the Motorcraft FL1A filter. Should be available at a Wally World near you.

 

What should the oil-psi be reading, at 55mph, and at an idle ?

 

What is the best oil to put in my truck & why ? 1979 F150, 400ci. Hum, we'll hope it doesn't leak oil, if it does stay away from sythetics. For most buying oil is just a personal preference, one brand verses another is not where it's at, as long as you change it at regular intervals, any off the shelf oil will work. providing you don't buy non-detergent oil. I would just go to your local auto parts and buy(Valvoline,Quakerstate,penzoil, or another) in a staight weight I would run a 30wt, and a 10/40 or 10/30 in a muti-viscosity.
although as our engines get older they sometimes need a little thicker oil.

Also, what should the oil-psi be running, & at what mph ? well if you have a factory guage in your truck? anywhere in the normal range will be fine. where I come from they say at least 10 psi for every 1000 RPM, but that only goes so far. we all know fords gauges aren't the most accurate. so on a mechanical gauge at highway speed(55-70), 40-60 PSI would be great.

Oh, congrats on learning how to do it yourself. -RW
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Before 1986, Ford oil pressure gauges were real, it is the later ones that cannot be trusted, idiot light with a needle. Going for high oil pressure as a measure of engine health is not necessarily good. 60psi hot is generally too much for a stock engine. Either you are using SAE 50 or there is a blockage somewhere. I would start with Delo 400 15W-40 and see how it goes. I used that oil all year in an old 302 here where winter-summer temps range from about 20-100F.

Jim

 

My oil pressure is caused by proper clearances on my bearings. & a Hi-Vol pump. not high pressure. thanks for the concern though. -RW