And I can get 20mpg... so how much harm can it be doing?

 

I use it in my 89 runs smooth and haven't had any problems out of it

 

I use rotella 15w-40 in my Honda trx450r wheeler in the summer and switch to rotella 10w-30 for the colder months and to store it in the winter. I switched from mobil 1 synthetic to rotella because it is dirt cheap and runs much smoother and cleaner than the Mobil. And its only $11 a gallon!

 

Been running Rotella 15w40 for a couple years now...224K on the ticker and no problems yet. I also have used it in my '81 F150 (302 V8) without any problems.

Sure, it's a little thicker than 10w30, but if it can handle being in a dirty old compression-ignition engine, it can certainly do fine in a little gas engine. Besides, it meets the oil specification for the 4.0 anyway (I think the 15w40 is an SM oil...if I recall the Jeep owner's manual calls for a rating lower than that). Once it's heated up, it thins out moderately. As I said, I've had no problems with this oil.

Personally I recommend running Rotella 15w40 with a Wix filter. Stay away from Fram if at all possible, I have read stories about everything from lowered oil pressure when using a Fram to hearing how the filter media disintegrated inside the filter housing.

 

Thanks man! yea FRAM makes a terrible product ive never used them and never will. Im running an STP filter now and have been pleased even though its also produced by champion labs. ill probably change to a NAPA GOLD or somthing in the near future. Just feelin out what my XJ likes and dislikes right now ya know.

 

No problem! BTW I think Napa filters are made by Wix.

Something I've considered doing between oil changes is changing out the filter. Change your oil like usual, every 3,000 miles, 3 months, 6 months, whatever, but halfway through that time, change the filter. That way you have better filtration during the time you have the oil in the motor.

I never get any valve noise or anything with Rotella. Not even overnight. I get a little if my truck sits more than overnight, but that's normal. It goes away after oil pressure builds up.

 

i run napa gold in my jeep and my honda civic. good filters, cant say anything bad about them.

in my jeep i'm running mobile 0w30 and it seems to like it. i only get about 5 seconds of lifter tapping when i start it after sitting a few days. if i drive the jeep every day, there is no lifter noise. and that is with 237,000 miles on the jeep motor.

with gas at $3.87 a gallon here, i predict i'll be driving the civic alot more.

 

I think that rule only applies for gearboxes/differentials since the agitation of the oil causes the heat build up but in an engine, the combustion is the heat source and the oil helps absorb some of the heat...? Never really got a clean answer on this. On my car, I'm going after the high load capability, with little breakdown, of the diesel oil since diesel oil doesn't have friction modifiers in it and almost no detergents. A lot of guys run this on high boost applications like mine. I had a girl friend with a 91 Toyota Corolla that started knocking and I put some of that 15w-40 in as a last ditch effort to keep it alive; the whole car was looking pretty rough. The good news was that it pretty much stopped the knocking but it wouldn't like to warm up completely after that. If you let it sit, sure it would get to operating temps but driving around town it would drop back down. In my 2.0L boosted motor (SR20) I noted a similar drop in operating temperatures, when driving normally. But through out a drift event its been the only thing that holds up well.

I also run that 15-40 in my Suzuki TL1000R, but it requires that and again since diesel oil doesn't have friction modifiers in it, its safe to use on a wet-sump clutch.

 

I always ran 10-30. I tried the 15-40 but with 250,000 miles I dont think the oil pump did. With the thicker oil it created greater friction therefore lowering my oil pressure and causing a worse tick. When I switched to 5-40 the oil pressure was better than normal and the tick was gone. Not saying the same will happen, but it goes to show the science is correct.

 

This slide speaks for it self..

 

I run Delo 15w40 in everything i own and have for hundreds of thousands of miles with no ill effects in all brands of gas engines.
One, because I like the added detergents in "diesel oil" to keep the motor clean, and 2, because ive still got about 150 gallons of it left to be used.

 

BS. There's no way that pic is room temp. Rotella 15w40 is only slight thicker than 10w-30. Rotella 5w40 for winter, 15w40 summer. They are right next to each other on the self in walmart.

 

X2

 

That slide kinda goes along with Dr. Haas's Motor Oil dissertation.

 

Its at cold which is not bs but dont take my word for it read a MSDS or spec sheet on your oil and compare for yourself. Below is the link to the writeup and this is related to flat tappet. dont forget 40c=104F so thats not "cold". Hope this clears up your doubts.

http://www.widman.biz/uploads/Corvair_oil.pdf
pg. 6 of 31


For a Graph view:
http://widman.biz/English/Calculators/Graph.html