Handful of Dumb Questions from a new owner

Well, it looks like unsolvable oddness. I've got the right dipstick, I've got the right pan (I would assume AMC didn't weld skid plates on automoble oil pans) and I've got a 5qt capacity, yet others with the same have a 6qt capacity. In the end, probably doesen't matter that much, so I'll just stick with the 5qts. Another one of those Jeep oddball deals with no solution. The German in me would really like a rational, logical explanation for the difference, though. Shallower pan with more GC wouldn't bother me though. Aww, now I gotta go out and do a depth measurement. I hate being German sometimes.

 

Measured my pan. Looks to be 8 3/4" from the bottom of the mounting flange to the bottom of the skidplate. I wonder if the pan changed when AMC went to the lighter 258? I think I remember reading that the older engine had more main bearings. I don't really know when AMC went to the newer 258, but if it was in 1976, and the pan is slightly different between the two engines, that could explain why Tim's 77 takes 6 and my 75 takes 5. Pan could have changed shape, too, I guess...

 

Not main bearings ... the number of counterweights changed. All modern inline 6s have 7 main bearings.

The newer "lightweight" 258 started in 1981. The '75 engine is the same as the '77 engine, except mine was the first year for the 2V Carter BBD, and then only in full-sized Jeeps. I don't know of any other differences.

 

As Rick said, if you are getting good oil pressure with 5qts (or whatever you've been using) then don't worry about it. Go with what has been working. That engine would have blown up years ago if you were doing something wrong or bad.

If its getting good oil, thats all that matters. The rest is just un-needed worry.

 

Thanks guys. I't not that I'm worried. I would just like to know what the difference is. Simple curiosity. A character flaw, I guess.
The brew idea sounds good to me.

 

My boss is German. Working for someone who demands rational logical explanations for everything is FUN!

 

I asked once already, but what is "good" oil pressure? 20psi??

 

I might have figured it out, is your dip stick straight or arched? mine is arched meaning that the tip will be higher than yours because of the distance the tip travels left and right versus up and down, meaning that i have to put more oil in my pan to reach full. Maybe i should un-arc my dipstick....

 

Oil pressure at least 20 after warmup your good to go.

If not or you lose oil pressure often then put more in.

Just dont overfill and all will be fine.

Hows your tire pressure's now that something to worry about.

 

Straight dipstick. Thick, Strong. No flacidity like your current generation of dipsticks.

I'll probably go to hell for that, but some chances only come along once in life.

 

Crossed my mine but I like it here and want to stay.

 

I have noticed that when I am running the engine in gear the pressure is above 20 but when I come to a stop light or idle the engine it starts to drop off a bit.

As far as the tire pressure, it depends on what trail I'm running.

 

Your pressure will fluctuate with engine speed.
Sounds like your pressure levels are fine.
Yes, I believe 20psi is just fine.

 

Mine had been fluctuating quite a bit, so I took a look under the hood. I noticed that I was seeing some oil creep up the dipstick and out onto the engine. I pulled the dipstick and noticed it was very loose. I stretched the metal just below the handle, it went back in nice and snug. Fired the engine up and sure enough the oil pressure was holding right around 20psi again.

 

and i agree with you. i've been changing the oil once per year on my '75 258 for the last 15 years, and i've always used 5 quarts of oil, including a changed filter. 6 would be too much for mine.

i'd add 4 quarts, and then add 1/2 qt at a time until the top mark is met on the dipstick, once you find the dipstick.


also, my '75 tech manual does claim 6 qts with filter, but i've never used more than 5. full is indicated at 5 qts. also, i used a napa 1258 filter (big) for years, and now i use a wix gold 3258 ?? large filter.