Oil

[SchneiderFishing]

So is there any kind of agreement on what oil to run in this old trucks.

20/40 High milage or 30?

[CRF136N]

I think it really depends on the weather where you live. If it gets cold, you don't want to go too thick. If it gets hot (or you have burning/leaking issues), you don't want to go too thin. I used to run 10/40 (used a little, dripped a dab here and there), but this last oil change I switched to Delo 15/40 (more or less same as Rotella) Everyone raves about it, and it seems to be a happy medium between too thick and too thin, and its still reasonably priced. Here in Tahoe it gets in the 70's in the summer, and the 20's in the winter...I plan to stick with Delo 15/40 5,000 mile oil changes from here on out...for what its worth.

:cheers:

 

-James

[Eagle]

So is there any kind of agreement on what oil to run in this old trucks.

No

 

20/40 High milage or 30?

IMHO, high mileage oil is a scam that some of the oil companies use to charge more for what is essentially the same product. Whatever type and brand of oil you choose, do NOT use a straight weight (30, or any other) in an MJ. The factory spec was 10W30 or 10W40 for most climates. You want the thinner viscosity (the first number) for getting early oil flow to the critical areas on cold starts. You want the higher viscosity (the second number) to maintain a good oil film when the engine reaches operating temperature.

 

For my '88 MJ at about 125,000 miles, I run Castrol Syntec full synthetic 10W40. For the '88 XJ at 280,000+ miles, I'm running Castrol Syntec 20W50. I switched the XJ over to synthetic at 175,000 miles. I bought the MJ used with 99,000 on the odometer and started using synthetic in it when I bought it.

[CRF136N]

20/40 High milage or 30?

IMHO, high mileage oil is a scam that some of the oil companies use to charge more for what is essentially the same product.

I hesitantly/doubtfully switched to High Mileage Valvoline in my '02 Toyota Tundra at 150,000 miles because it started using about a quart of oil consistantly every 3,000 miles...Immediately upon switching, it stopped using oil. The high mileage stuff actually has a different hue and a significantly different smell, so there is something different about it. If I still had that truck :cry: I would still be running it. In the case of the 4.0 though, the tolorances, etc aren't what the newer designs are, so you can be a little more lenient on how you treat the motor. I had briefly concidered a synthetic oil for my MJ, but I just feared the worst with leaks popping up everywhere, thats why I just went with a heavy duty affordable oil and called it done.

:cheers:

 

-James

[CRF136N]

:hmm: Wow, I have REALLY been sucking at this quoting thing rescently...sorry :nuts:

 

-James

[comanche09]

For my '88 MJ at about 125,000 miles, I run Castrol Syntec full synthetic 10W40. For the '88 XJ at 280,000+ miles, I'm running Castrol Syntec 20W50. I switched the XJ over to synthetic at 175,000 miles. I bought the MJ used with 99,000 on the odometer and started using synthetic in it when I bought it.

 

Castrol Syntec (except 0w-30 German origin), and most of the rest of the oil brands "Synthetic" oils are not a true synthetic, but just highly refined/additive package parafin (dino juice) oil. Not much better than regular old dino and IS a ripoff.

 

http://www.bobistheoilguy.com

 

Mobil 1 Synthetic IS a truly synthetic oil and is readily available (walmart). Amsoil, Royal Purple, Redline Synthetics are also true synthetics, but not readily available to most. I run Mobil 1 Synthetic 10w-40 High Mileage and it is the same price as regular Mobil 1 Synthetic 10w-40.

[RLCollins]

As new member to this club. I want to thank whoever put this website together. It has been informative for me. I find that my 1989 MJ long bed with a 4.0 HO and 162K miles runs great on regular 20w50 Castrol oil. That's the only oil I have ever known for the past 25 years. I buy it by the case. I ran it in my Suzuki GS750 2 wheeler which was a FAST crotch rocket, I ran it my E-350 Ford, and I ran it in a Toyota Corolla. It seem to work fine "IF" you live in warmer weather like where I live in South Florida. The Chrysler Motors book 81-326-9052 that came with my Jeep MJ says to use engine oil of API Quality SG or SG/CD SAE 10w30 Preferred. If you look inside the book on page 69 it tells you 20w40 or 50 which are good down to 30 degrees, 10w30 or 40 are OK down to 0 degrees, and if you are going below that use 5w30, it is good up to 60 degrees on the high side. But I know very little about the preformance of these oil grades or the manufactures. Maybe this will help :hmm:

[Eagle]

Castrol Syntec (except 0w-30 German origin), and most of the rest of the oil brands "Synthetic" oils are not a true synthetic, but just highly refined/additive package parafin (dino juice) oil. Not much better than regular old dino and IS a ripoff.

 

http://www.bobistheoilguy.com

 

Mobil 1 Synthetic IS a truly synthetic oil and is readily available (walmart). Amsoil, Royal Purple, Redline Synthetics are also true synthetics, but not readily available to most. I run Mobil 1 Synthetic 10w-40 High Mileage and it is the same price as regular Mobil 1 Synthetic 10w-40.

Not true.

 

The original Mobil-1 was synthesized from "stuff" other than oil. Other brands, including Castrol, were synthesized by heavily modifying the molecular chain of petroleum base stock. Several years ago, Mobil took the other companies to court and claimed that they should not be allowed to advertise their products as synthetic, since they began life as petroleum products. The court reviewed extensive petroleum industry and SAE documentation as to what the definition of "synthetic" was, and how its properties differed from conventional oils. The court's conclusion was that the other brands had all the same enhanced properties of Mobil-1 and satisfied all functional descriptions and definitions for "synthetic" oils. Mobil lost the suit.

 

Within a few months, Mobil-1 had new packaging announcing a new "improved" formulation. Which was putting their spin on the fact that they switched over to making their synthetic oil the same way the other guys were making it. They are not just highly-refined dinosaur juice with an additive pack, and they ARE significantly better than conventional oils.

 

http://motorcycleinfo.calsci.com/Oils1.html

[jpdocdave]

i use valvoline max life 10w30. the higher mileage is 2 dollars more a 5 qt. container than regular stuff at wally world, and i have been happy with it. the top end of mine is all new, the bottom end was all leaking, oil pan, rear main? oil filter adapter, i've been using this oil for a year or so and its stopped leaking all over the bottom, i was shocked last time i was under it. and no its not because the oil all leaked out, its full :nuts:

 

i do belive though that changing the oil regularly is beneficial for seals and such. since i see so many cars on a daily basis in the shop, i've noticed that cars that prolong oil change intervals seem to have more leaks. i think molecularly the crud and crap floating around after all that time damages seals, just my screwed up opinion.

 

and speaking molecularly, i do belive that synthetic oil can be more likely to leak on a high mileage engine, and everytime i ask an oil rep they say the same. synthetic has a more consistant and smaller molecular structure (think of a bucket full of golf balls) dino oil has more spurratic, and less consistant molecular structure (same bucket full of golf balls, tennis balls, baseballs.....) i won't say synthetic oil causes leaks, it doesn't, but, a worn seal may be more likely to leak when synthetic oil is used.

[freakjeep93]

i use good old 10W 30 reglar oil for my porpuses in both my atv and both my trucks but i live in coldland so you might not want it as light

[Eagle]

i use good old 10W 30 reglar oil for my porpuses in both my atv and both my trucks but i live in coldland so you might not want it as light

Up "nawth" where you are, you probably should be running 5W30, at least in the winter.

[comanche09]

Not true.

 

The original Mobil-1 was synthesized from "stuff" other than oil. Other brands, including Castrol, were synthesized by heavily modifying the molecular chain of petroleum base stock. Several years ago, Mobil took the other companies to court and claimed that they should not be allowed to advertise their products as synthetic, since they began life as petroleum products. The court reviewed extensive petroleum industry and SAE documentation as to what the definition of "synthetic" was, and how its properties differed from conventional oils. The court's conclusion was that the other brands had all the same enhanced properties of Mobil-1 and satisfied all functional descriptions and definitions for "synthetic" oils. Mobil lost the suit.

 

Within a few months, Mobil-1 had new packaging announcing a new "improved" formulation. Which was putting their spin on the fact that they switched over to making their synthetic oil the same way the other guys were making it. They are not just highly-refined dinosaur juice with an additive pack, and they ARE significantly better than conventional oils.

 

http://motorcycleinfo.calsci.com/Oils1.html

 

Interesting. It's been a few years since i've looked at oils in depth. Bummer about Mobil 1... :( Do they produce any true synthetic anymore? My main premise for using it is its resistance to sludge buildup vs conventional dino.

 

Can't blame them I guess, as their competitors were enjoying a much bigger profit margin (ie ripoff for the consumer) peddling their "synthetic oil".

 

Are Amsoil and Royal Purple still real synthetic oil? Perhaps it is time to local my nearest Amsoil dealer :wall:

[ComancheKid45]

Ive been lead to run 15w40 in the 4.0 so I run it in both my Jeeps and my Dads YJ without any issues :thumbsup: 3000 miles on intervals as well

[CRF136N]

One more point with my experience I forgot to mention...about late Aug this year I noticed my MJ (with the '94 HO 4.0 with 164k on the clock) began to dry start...that chilling top end clack-clack-clack for the first 2-3 seconds it would run, got progressively worse to be consistant about 70% of the time. I was using 10/30. I tried using Lucas additive...nothing changed. I changed it to 10/40...again, no difference. I then put in the 15/40 delo...and 2,500 miles later it hasn't done it since :dunno: As a service tech myself, I am a firm believer in manufacturer specs, but I think it gets to a point after about 125-150K on the clock, especially if you don't know the full history of the vehicle, that you personally need to re-write your own rules from trial and error to your specific situation, and what seems to work for your truck best. :cheers:

 

-James

[87Warrior]

We had a small discussion here:

viewtopic.php?f=2&t=19409

 

As you can see, there is no universal agreement on oil. I use a 10w-30 AECA A1/A5 or A3 oil. You can see the discussion in the link ;)

 

I am running Castrol Syntec (or Vavoline Synthetic in a pinch) 10w-30 in my MJ with 200,000 miles on the factory engine. She runs great down the road, but does tend to drip a little bit out of the RMS with the synthetic in there. When I got the truck, I did an oil change (185K) and the goop that came out was the most putrid black oil I ever saw or smelled. Now with regular synthetic changes, the oil improves in smell and appearance each oil change. It is important to note I am running the HO 4.0, not early style(87-90), so the head is slightly different.

 

Oil Filters are a fun discussion to. I run a Mobile 1 or Bosch filter. My reasoning can be found by studying the links below:

http://minimopar.knizefamily.net/oilfilters/index.html

http://www.rubiconownersforum.com/phpbb ... 38&t=58887 (not sure if you can open or not. The same study done buy a tech on the Rubicon forum)