oil and oil pressure question.

[Dano]

I was told to use "non-detergent 30 grade oil ONLY" in my 52 m38 (w/L4 134), otherwise it would be bad for my engine. My jeep sat for at least 20-25 years before bring it home, I changed all the fluids, rebuilt starter, blah, blah, blah. Anyway to make long story short, I put in some cheap 10w-30 oil. I got the motor running, runs great by the way, now I'm want to change the oil again, clean out the oil pan/screen.

Questions:
Can I use standard 10w-30? (since I've already done so)
Oil pressure gauge reads almost 60 psi steady @ 30mph, is this too high?

Drops to 55psi when standing.
Some manuals say 35psi other manuals said 50psi @ 30mph

This jeep has been civilian-ized (engine may have been rebuilt in the 1960's)
and it was changed to 12 volt system.

Thanks to all who respond.
_________________
Danny
MVPA # 32807
1952 M38 MC 70731
1946 Bantam Trailer
1983 CJ7

[maeserik]

Is your elecrical driven pressure gauge exact ?
My electical gauge indicates 50 psi (full scale)during driving, and about 30 on warm idle, so far this is exact. When i start the cold engine, after a few seconds the needle jumps to 50 psi.
I would not worry, i use mineral 10W40 already 4 years, with no problems.
Once a year i replace the oil. You have oilpressure, even on idle and with a warm engine, so nothing to worry about. Just enjoy your jeep !

just my opinion.
Erik
_________________
1942 GPW 71336 my son's jeep restored now
1951 M38 MC11891
1953 VW beetle (genuine german Käfer )
1957 fantastic wife

http://www.surfacezero.com/g503/showgallery.php?cat=1865

and this webside

[oilleaker1]

10-30, or straight 30 is good. Cleaning out the pan and screen after a long storage is important. Oil settles out over time. Looks great on the stick----Ha! Pull the plug on the pan and stick your finger in and check the pan bottom . Mine is coming off for a good bath. I've heard of running automatic transmissin fluid( full ) to flush and clean, but if you don't first send all the oil through a filter, I wouldn't do it. Jeeps send only some, not all oil through their filter. Cleaning out and a new gasket is cheap insurance. John PS- if you clean it out, make sure you prime the oil pump and gallery before starting. You can do this with a finger pump oil can and squirting it into the gallery where the oil pressure tube leaves the block.

[wesk]

First for the oil pressure reading accuracy must be ascertained on day one. If you have a direct reading type gage then check that one with another direct reading type gage and compare. If you have an electric sender send up then get a direct reading type gage and plumb it in to compare readings. The M series senders available today surplus seem to vary quite a bit in accuracy.

Oil names can be confusing.

[b]STRAIGHT[u] mineral oil is exactly that, no additives. It was used a lot until the 50's. It is still used by most folks on a freshly overhauled engine to help the break-in happen sooner by leaving a little extra friction for the rings to run in.

Don't confuse [b]STRAIGHT[u] mineral oil with [b]STRAIGHT[u] weight oils. The terms do not mean the same thing. The first deals with the composition of the oil and the second with the viscosity of the oil. The term [b]STRAIGHT[u] combined with the term weight is only to help differentiate between the [b]STRAIGHT[u] weight 20 or 30 or 40 or 50 oils and the variable weight (or multi-weight) oils like 5w30, 10w30, 10w40 and so on. As you will see [b]STRAIGHT[u] weight oil is available in mineral or semi-synthetic.

Semi-synthetic oils are the most common today and they are of course better since their lubrication abilities are greater, They come in the [b]STRAIGHT[u] weights 10, 20, 30, 40 and so on and in the multi-weights 5w30, 10w30, 10w40 and so on. They are usually not good to use when breaking in a fresh engine but are a definate improvement over the mineral oil for longevity of your engine.

Full synthetic oils (Man made compounds) are expensive and in my opinion not worth their price for older cars and trucks.

Why do most of the old manuals list only the common straight weight oils? Well the older engines up through the 60's had greater bearing clearances and the thinning of the oil as it warmed up caused a loss of lubrication effectiveness when too light a weight oil was used. Multi-weights have many advantages but the disadvantage I like to point out is they are too thin when cold and this causes a little more wear of your old large clearance engine on start-up and initial warm up. With old flat head engines I like to use the correct weight for the season and I try to stay with single weights (straight weights) here in Wisconsin 30 summer and 20 winter.

What should operating oil pressure be? 30 to 35 PSI at cruise and 10 at idle hot. Too much pressure is not always a good thing. It can burst hoses and cause seals to fail. 55 to 60 should be the absolute max when cold. 50 should be the max when warm.
_________________
Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php