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help me decide which oil to run

O

outlander

NAXJA Forum User
Location
Columbus,Ohio
89 xj 4.0 fresh motor with around 12k on it.

I have narrowed it down to these choices:
Continue with the conventional mobil clean 5000 which I current am running(10w30).
or.....
walmart's "super tech" brand full synthetic 5w30 or 10w30(cheapest full synthetic I've found)
or.....
rotella full synthetic 5w40(dont really know about this one because my oil pressure seems kind of high)this one seems to have better anti-wear qualities judging by the certifications on the bottle

what do yall think?
What benefits will I see by going to synthetic besides less sludge?Will my engine run quieter?

I hate sounding like a newbie!!!
 
i've been running Mobil 1 10-30 high mileage for summer and 5-30 winter for the past 10k
I also experienced stuck throttle 3x's and 7000 each occasion (floor mat gone now)
My sticky lifter seems to be slowly going away
 
Noooo, an oil thread... :)
I'm running the Rotella-T syn 5w-40 at the moment. I'll only put that or Delvac 1 (Mobil's equivalent HD oil) in the heep these days. Both are still SL with 1200ppm zddp easy. Simply robust oils that can be put in about anything thta calls for motor oil.

Mobil-1 Turbo Diesel Truck oil(fully syn, 5w-40) is great stuff as well. ( Delvac 1 rebottled for a different market)

Can't beat teh 16 dollar 4 qt jugs of the Rotella T syn right now at walley!!
 
Stay away from the SM rated oils. Engine death in a bottle. I think the equivilent death diesel oil is CL?

Use them and say goodbye to your cam and lifters. Roller lifters will be just fine with them but flat tappets go bye-bye in short order.
 
Eliminator89 said:
Stay away from the SM rated oils. Engine death in a bottle. I think the equivilent death diesel oil is CL?

Use them and say goodbye to your cam and lifters. Roller lifters will be just fine with them but flat tappets go bye-bye in short order.
Click to expand...


x2

But you want to use an oil with a higher amount of ZDDP. As its the last line of defense in case of viscosity breakdown.

A good quality synthetic will make your engine run cooler, improve MPG, and reduce engine wear. Once the crud cleans out of the engine, your engine might running quieter. It really depends on the underlying reasons behind the noise in the first place.
 
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I thought the lack of ZDDP was only going to effect those with higher spring rates and aftermarket cams.
 
Harlee&Tahoe said:
I thought the lack of ZDDP was only going to effect those with higher spring rates and aftermarket cams.
Click to expand...

Its going to effect anyone if you reach the point where the oil begins to experience viscosity breakdown...

Higher spring rates and a longer duration cam is going to make the problem appear sooner.
 
w_howey said:
Its going to effect anyone if you reach the point where the oil begins to experience viscosity breakdown...
Click to expand...
How long before viscosity breakdown occurs? Also, how can you tell?
 
Harlee&Tahoe said:
How long before viscosity breakdown occurs? Also, how can you tell?
Click to expand...

Depends....

Quality of the oil you are beginning with, conditions you are subjecting the oil to(driving style, heat levels, engine condition,etc.)

You can't really look at oil and see its approaching V breakdown. If oil is starting to look bad, smell bad, etc. you are there or rapidly approaching the edge of the protection offered by the oil.
 
so that being said if you change these new sm rated oils before they break down will that counter the lack of zddp?
you sound like an amsoil distributor....wait you are!!! j/k
 
how does amsoil stack up in the zddp dept.?
It's really too bad for us flat tappet gasoline guys that diesel oils can only be found in diesel weights....is it really that big of a deal if I run 15w40 as opposed to 10w30?My motor is fresh and tight,rebuild was only about 12k ago.I'm afraid to run 15w40 in this cold weather we are having here in the buckeye state.Got down to 9* last night!!!
Maybe I'll go with the 5w40 rotella syn....
Concerning the super tech full syn: Does the fact that it is fully synthetic make up for the lack of zddp?
The aftermarket(such as amsoil)needs to come out with a zddp additive we can use to boost these new sm oils up......damned government!!!
 
Last edited:
Keep in mind the newest diesel oils are also way down on zinc. There are no longer the fix.

Guys on the classic car forums I hang out on have also run into the cam problem. They thought there was a run of bad cam blanks but it was the new oils that were doing the damage. Strong springs cause an earlier failure.

I look for SL or older oils. I have a small stockpile now. GM's EOS oil supplement was a good source of zinc but they have pulled it from the selves. The dealers were told to return it. If you can still find some, buy it.
 
I'm afraid to run 15w40 in this cold weather we are having here in the buckeye state.Got down to 9* last night!!!


Wow that would be nice here it was the high yesterday lol I've just been using Mobil 1 10W 30 summer and 5W 30 winter. As far as the Zinc thing could't tell yah. My weakness is chemistry. I now have been running the Mobil one in her for 40000 miles now with no problems other then the slight piston slap when I bought it. Never gets louder or quieter but go's away the minute she's under load or throttle.
 
Well If you arn't leaking any oil out and not burning any I would go with amsoil 10w30 Best oil for the price
 
w_howey said:
x2

But you want to use an oil with a higher amount of ZDDP. As its the last line of defense in case of viscosity breakdown.

A good quality synthetic will make your engine run cooler, improve MPG, and reduce engine wear. Once the crud cleans out of the engine, your engine might running quieter. It really depends on the underlying reasons behind the noise in the first place.
Click to expand...

It'd be nice if synthethic oil would quiet noisy cracked exhaust manifolds :yelclap:
 
Can't go wrong with Rotella "T". I use it in my 97, 01, and my two motorcycles, 1974 Kawasaki Z1, and my 2002 Honda 919. If it's recomended for my 919, with it's anti-ware additives, it will do just fine on my XJ's IMO.
 
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