Oil type/grade for AMC V8

I've had a look at the owners manual and its suggesting a 10w30, 10w40 or 20w40 for my conditions, what oil does everyone recomend, its hard to find mineral oil in Ireland will semi synthetic be ok?

 

When i did my engine rebuit by a professionnal e told me to use 10w40 synthetic or non synthetic...if you go synthetic you wont be able to come back to normal one. Other thing i suggest is to put an additive of zinc into the oil. It cwill help to prevent engine damage at long term

 

I wouldnt use a synthetic till the motor is well broken in the advanced lube properties of a synthetic wont seat rings or break in the cam....my 2c

 

Changing from regular to synthetic doesn't CAUSE leaks, it reveals leaks you already had that were packed full of junk from the conventional oil you'd been running forever. So changing to syn can shake junk loose. My Harley, which never leaked before, started dripping furiously when I changed to synthetic. I found the rocker box gaskets were terribly dried and cracked. Synthetic didn't cause my gaskets to shrivel and crack but the junk from the old oil held the leaks back.

 

X2. Synthetic oil is so slick it won't allow metal parts to "wear in" to each other, if you've recently rebuilt the engine. (Never witnessed it first-hand, but it makes sense to me.) X2 on johneyboy03's recommendation for a ZDDP (Zinc something-something phosphate) additive, too. Once again, never experienced it first-hand, but it was taken out of the oils in the early 90's and anything with a flat tappet camshaft is prone to much-accelerated cam wear without it. ZDDPlus is what I use in my '85 GMC big block and will use in my other engines... whenever I get them running.

On second thought, you might want to research ZDDP in your oils. I'm not sure if ZDDP was taken out of all oils (worldwide) or only American oils, but if Ireland already has adequate ZDDP levels in the oil made there adding more could be unecessary and possibly detremental.

 

You can change back and forth between synthetic and conventional oil. There is no reason you can't, That's just an old wives tale.

A synthetic or semi synthetic in the proper weight (generally 10w-30) will run just fine in your jeep.

As far as the zinc levels, I'm sure in Europe they are the same or even lower than US oils. While a zinc additive will not hurt your engine, and is reccomended for flat tappet cams, its not neccessarry in a AMC motor that is running well. Zinc provides a "last line of defense" under extreme conditions and can help reduce overall engine wear.

That being said, I run 15w-40 diesel grade motor oil in my AMC 304. I do this for 2 reasons, it helps increase idle oil pressure and it contains higher levels of zinc than convetional gasoline engine motor oils (At least in the US, I would suspect that this also applies to European oils)

 

My engine rebuilder suggested the same...specifically Shell Rotella 15w-40, at least for the break in period of 500-1000 miles. Otherwise a good quality multi-weight oil appropriate for your climate should be fine.

My preference would be to check the SAE tables

 

I am running Brad Penn Grade 1 partial synthetic in my rebuilt 283 (from a '66 chevelle). The engine has a flat tappet cam and I was looking for an oil with Zinc (Oenn Grade 1 has it). The straight grade Rotella has not changed the Zinc content but the other Rotella grades have lowered the Zinc content due to new government standards. I went through this issue when choosing the oil for my engine. I wound up with Brad Penn, the green oil. I am happy with it so far...also using Wix filters...

http://www.lubereport.com/e_article000288578.cfm

 

I run 15-40

 

ROTELLA 15-40 here also. it helped my warm idle oil pressure. my 360 only has about 400 miles on it but I am only getting about 12-15 psi at warm idle, roughly 750 rpm with the rotella with 10 -30 i was at 10 to 12 psi.

 

I’m a fan of Rotella too but for break in I’d also throw in a bottle of engine break in additive like a bottle of Comp Cams additive.
That is partially because I’m a “Bow Tie” guy and Chevy mills are notorious for knocking cam lobes flat during break in. I don’t know that AMC mills are as bad as Chevy but it certainly doesn’t hurt to throw some additive in just in case. At worst it’s a little more lost money when you drain the break in oil.

http://www.summitracing.com/search/...es/Part-Type/Motor-Oil-Additives/?Ns=Rank|Asc

 

10W40 here.....usually whatever is on sale, and change it before each hunting season.....only put about 2K/yr on the CJ. The engine runs at about 180-210 degrees in the Valley and it can get well over 110 degrees for extended periods of time here. No leaks. No issues.