Engine oil: what type should I use?

Engine oil: what type should I use?
1980 CJ7
On my 1980 CJ7 that I baby to death, I dunno what type of engine oil that I should use in order to enable the most life out of it?

I never take it in rain, and only drive it a couple times each weekend! It will be sitting during the week in a dry garage.

I am wondering the best things that I could do to make sure this engine and transmission stay in great shape?

It is a AMC 258 i6 / 4.2l straight-six engine with 65,000 miles on it... Everything original except for new carb, new radiator!
Since you baby this thing and don't really spend a lot of time driving it, there are a couple ways of looking at this.

1) You don't put enough hard wear on it so just good old recommended oil is fine.

2) You don't put enough hard wear on it so a special oil would be better because of it sitting all the time.

I'm a big fan of synthetics if I don't have to change the oils all the time (water contamination).

I would run all synthetic lubes and then you can just about double your change intervals (not the filter though - that still has to be changed at the correct interval).
BAH! you're crazy! :D good old dinosaur oil is king!! Seriously, syn oils are good, but spendy as hell. I am a firm believer in regular maintainence and 3000 mile changes. I honestly don't know if the brand makes a hell of a lot of diference under those circumstances, as long as you use the correct visc.. I use Castrol GTX, only because I have for more years than I care to admit. Even with high mile tear downs, the engines have been clean, and shown only normal wear. I think It all boils down to doing the changes on time, and you're good to go.
Well since it sits more than you drive it I would use a synthetic. I believe they leave a film that hangs on longer, that way you don't have a dry start up.
I use mobile 1 in both my truck and my jeep. They both sit more than they get driven. I also change the oil & filter every 3000 miles.
With 65K and 29 almost 30 years on probably stock gaskets, and you haven't ever ran synthetic fluids in it before I personnally would NOT change over to full synthetics. Synthetic fluids have a way of finding weak points in gaskets that conventional fluids don't. In other words, if it doesn't leak now, and you decide to switch over to full synthetics, you may find leaks that weren't there before.

My CJ probably sees the same amount of driving yours does. I may have put 5,000 miles on it over the past 2 years. My personnal preferance is Valvoline High Milage (partial synthetic) 10W-30.
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I love synthetics, in engines that are modern and with seal, gaskets and other stuff that are engineered for them.
but our engines in these things were made in the dark ages as far as these items are concerned, So I look at the recommended manufacturer specks, then I realize oils have improved so I use the modern multi viscosity equivalent for the oil recommended. I have seen a brake system tear its hydraulics to pieces using a modern synthetic fluid, I took a big lesson from that and now use the syns in modern stuff, the dyno juice in older.
Also when I changed my oil on sunday, it was extremely dirty... What can be determined from this?

B/c when I Re-bought my jeep there is no telling when the oil was last changed...

should I change the oil again in about 1500 miles? I wanna think that this will help the engine b/c from the look of the oil that I last changed, there is probably still more dirt and gunk inside the engine...
on old engines you cannt beat maxlife. i work at a auto parts store and i alway ask how old and how many miles. my wifes 2000 civic has 108,000 on it and i only use maxlife in it. my 03 accord i run mobil 1 and a mobil one filter on it and change it twice a year and usually when i change it its not that dirty. i drive a total of 40 miles a day to work, i live in ohio and drive to illinois once on the oil change to see my family and once in awhile to a nascar race which there is none in my state so i rack up the miles on it. in the jeep i will probally run maxlife in it to when all my kendell runs out cause we stopped carrying it at work and i got a case for a dollor a qt.
Just as I though... Eight different answers and eight different opinions! It's a loaded question! :)
Mobile 1 but if you can get it get Brad Penn.
In wear prevention studies, it's gotten better results than royal purple.
I use Royal Purple in my engine and have it in my rear diff as well. I swear by it, and love the 4-5k mile intervals between changes (in my 06 4-Runner), and I will run it in my 360 when I put it in my jeep.
I wouldn't be worried about putting it in the old 6, and I bet you will notice a difference.
I've been using it for many years, and the only thing that I don't like is the price. It's about $8.00 a quart now! :eek:
I have the same question but no one but one person answered the question, Question was what type oil 10w30, 10w 40 10w90 0w90 15w 85, what oil and weight will be better, sorry for this post but Mobil, purple, Valvoline, GTX does not answer the question
This is from the 1979 service manual

above 40° 10W-30, 20W-40, 10W-40

above 0° 10W-30, 10W-40

Below 0° 5W-20, 5W-30
Old thread and no one mentioned a weight. These 6 cyls and V8s are a flat tappet camed motor, so a good 10w-30 or 10w-40 with an ZDDP addictive should be used. One recommended brand above was Castrol high mileage it may be a good choice. If the motor has alot of miles you could also use a 20w-40.
A good site to read about oil and additives is bobistheoilguy.com
Mine has had nothing but Castrol 10-30 for 35 years and sometime around 150K miles I switched to Castrol high mileage 10-30W and now have 238K miles and my engine runs great. The machine shop that did the work on my AMC 258 i6 / 4.2l I'm building highly recommended I use an oil with ZDDP. I'm a little torn on which way to go, since I have done so well with the Castrol oil

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