1974 F100 308 V8 2WD 180,000+ miles

Just bought it. It appears that the last oil change was with 20W50. What does this indicate about the engine health? I am going to clean the engine as there is a lot of oil and grime. Valve covers seem to be leaking and there is a small drip when first parked (2/3 good size drops). Thanks for the help.

Jim
NC

 

Jim: The 20/50 oil is basically a 50-weight with additives that thin it to 20W for cold starts. This may have been done for a reason - loose bearings or ? - or it may be what the previous owner had available when the oil was changed.

Sounds like once you have addressed the oil leaks and the like, you could go back to SAE 30W and see what happens - e.g. blue/gray smoke from the rings or knocking from loose bearings. There again, it may run just fine on the 30W.

Good Luck with your truck

Russ

 

Thanks very much for the reply. I will post my progress and findings as I move forward; and no doubt will have more questions for the forum gang.

Jim
NC

 

I have a little toy "Chevy" car that I drive every once in a while, when it isn't broken down with some major catastrophe. You see, they invented 20W50 oil because the engineers at GM still can't figure out how to make a small block engine that doesn't burn oil from day one.

So when you drive a small block chevy, you use 20W50 so you don't go driving around in front of a big blue cloud of stinky oil smoke as often then if you use "normal" weight oils. It gets kind of embarassing you know, with shiny mags, bright fresh paint, purring flowmasters and such, then go driving off into the sunset with a trail of blue smoke...not good for the image at all.

Its sad but true...this comes from experience.

I am sure 20W50 has other purposes such as what Ranger Russ said above. Its basically a thicker oil that will also hold up a little longer under high heat conditions...another hallmark GM small block charactaristic that was designed so they can force that 50-some-year-old 283 engine to comply with higher emissions standards. And you also have an outside temperature range that will allow temperatures down to 0 degrees, but I think you will start having some hard starting problems slightly below freezing with 20W50 if you have an older engine.

BTW, I didn't know Ford made a 308?

 

Sorry, a slip of the lip, I meant 302. Thanks for the input.

Jim
NC

 

Interesting? I am not saying this is wrong, but I have heard it two other ways. One (from an Amsoil rep) that the base oil is somewhere in between the two numbers of a multigrade oil and then polymers are added to give the higher number and pour point depressants are added to give the lower (W) number. The other one I have heard, and which makes the most sense to me ,is that the base oil is the W number and polymers are added to provide the higher number rating.

 

Well that clarifies things, Jim.

It was probably the same thing in your old 302. With 180K miles, you probably have a few things wearing out in the valve train, and the 20W50 was probably used to reduce the oil consumption and/or smoke. I just noticed that you are in NC, so that 20W50 might not be a bad idea for you until you do some restoration work on the engine.

 

Sounds reasonable to me. Thanks to all.

Jim
NC

 

i thought the 20w50 was for diesel engines

 

I believe there is a diesel 20w50 also, but 20w50 is made for gasoline engines. Not for your typical car though. Usually a 10w30 or 10w40 is sufficient. In hotter weather, you can use 15w40, the advantage over 10w40 being less viscosity improvers and a more robust base oil. If I lived in a very hot climate I might run 20w50 or if needed for oil pressure, or I may run it next summer, just not in cold weather (typically below 32 is not good with 20w unless you have an oil heater).

 

Naive gearhead,

I like Ford trucks as much as the next guy but to slam a small block chevy v8 shows your lack of automotive wisdom. Fords are superior to chevrolets in many areas but engines are not one of them. For the last 50 years or so Ford has played catch up to the GM small block v8 and has not caught them yet.

I'm not insulting Fords so don't get all jazzed up guys.

I just remember all the years when Fords v8's looked like someone dumped a box of vaccum cleaner hoses and parts in the engine bay and at the same time chevy had more power and less electrical crap to be constantly screwing up. Oops I forgot to mention a inferior oiling system as well. Anyone else besides me have multiple ford v8's throw a back rod? Another one, a way over complicated timing setup that was just way over engineered for no logical reason. GM kinda nailed that issue down 50 years ago.

Gearhead, I'm just asking that you limit your rants to things you understand. I don't post here much anymore but you can learn a lot from the regulars on here if you let yourself.

 

STAB !!!
where the heck have you been !?!?!?

 

Good to see you are still here Brian.