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Engine oil weight question

H

Holycow72

NAXJA Forum User
Location
Illinois
I have an '01 XJ with 43K miles. Next oil change I'm switching to synthetic. I've seen enough posts for me to decide with some type of 40 weight. Is 15W-40 too thick for Illinois winters? seldom below 0. Or should I consider a 0W or 5W-40 for winter and 10 or 15W-40 for summer? or pick an all-around?Which? With all the different choices, it gets confusing. And just to toss it out there...how about Castrol 5W-50? I'm afraid 50 is too thick. All imput appreciated. Thanks
 
I run Mobil-1 10W30 all year. Wife runs Mobil-1 5W30 in her oldsmobile. Kids both run Mobil-1 10W30 in their TJ's...
 
Re: RULE OF THUMB - OEM SPEC FOR FLUIDS

I work at UW with a large fleet of vehicles. I concider use of vehicle in our depatment severe. We run only what OEM recommends. Older rigs 95 and down 15W40.
Do you think Factory engineers are stupid. I know saving cost and all that, bla-bla-bla...
Thats my .02$.
Do what you think the best.
LET THE FORCE BE WITH YOU :worship:
 
Run the factory recommended weight for the temps you encounter. Special applications (non-stock clearances, etc.) call for changing that, but otherwise run what the factory says.
 
The manual for an '01 calls for 0W30 and that's what I run in mine. For the older ones that are well over 100k, when I switched to synth I went with Castrol 5W50 for the added hot viscosity. It isn't "too thick" ... remember, the second number is the hot viscosity, and hot 50-weight is a lot thinner than cold 5-weight or even 0-weight. It's just thicker than you need.

Thinner is better for intial lube at start-up, which is why a 15W40 isn't the best choice for winter use.
 
Interesting discussion. I've been running Delo 15-40 in all of my rigs (its a super oil for diesel apps), but I'm switching to 10-30 Mobil One in my stroker.

I have no clue how to pick an oil for a radicaly modified engine with forged pistons, anyone have a suggestion for a stroker?

CRASH
 
Mobil One makes a big rig synth you could run in your stroker. Cheaper than the auto oil as well.

Sarge
 
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Mobil 1 has a 0W-40. I'm no expert myself, but I chose to start using it based on the recommendation garnered from a multi-year run of oil analysis that I read on a forum (I think it was Bobistheoilguy?). After switching from 10w-30 I noticed oil pressure coming up quicker on startup and higher oil pressure at speed. Both were subtle. Note: My gas mileage also dropped 1-2 mpg around the same time. Could this have been because the oil is thicker at operating temp.?

EDIT: I found the link, and i was mistaken about the time period (more like months rather than years) but anyway it was good enough to convince me to try 0w-40. But don't take my word for it decide for yourself here.

Actually, now that I have re-read the whole thing - it doesn't say nearly as much about 0w-40 as I thought it did. But I haven't regretted switching. I'll probably go back to 10w-30 in the summer and see if my mileage comes back up.
 
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CRASH said:
Interesting discussion. I've been running Delo 15-40 in all of my rigs (its a super oil for diesel apps), but I'm switching to 10-30 Mobil One in my stroker.

I have no clue how to pick an oil for a radicaly modified engine with forged pistons, anyone have a suggestion for a stroker?

CRASH
Click to expand...
Bob Salemi has had his stroker running for about a year, and he's in Rhode Island so he gets seasonal temperature variations. You might PM him. If it never drops below freezing in your part of CA I think I'd go with synth 15W50, because the forged pistons fit a bit loose until they warm up. If it gets cold in winter, maybe the Castrol 5W50 for winter would be a good choice.

Much of the hoopla about thin oil for startup is really an excuse for better gas mileage. I'm old enough to have grown up before we had multi-vis oils. We ran straight weight 20-20W all year long, and if an engine started burning oil we moved up to 30-30W.
 
0,5,10,w #'s are your winter #. go with 0 or 5w-30 in the midwest winters and then 10w or maybe 15 in the hottest month's. it is the second # you need to pay attention to in the summer. the thicker the oil the harder it is on your oil pump, especially in winter. or move to Florida and run 10w-40 all the time!!!
 
Eagle said:
Bob Salemi has had his stroker running for about a year, and he's in Rhode Island so he gets seasonal temperature variations. You might PM him. If it never drops below freezing in your part of CA I think I'd go with synth 15W50, because the forged pistons fit a bit loose until they warm up. If it gets cold in winter, maybe the Castrol 5W50 for winter would be a good choice.

Much of the hoopla about thin oil for startup is really an excuse for better gas mileage. I'm old enough to have grown up before we had multi-vis oils. We ran straight weight 20-20W all year long, and if an engine started burning oil we moved up to 30-30W.
Click to expand...


It rarely gets below 25 degrees during the times I actually drive my Jeep, but it does get awfully hot in the summer. Regularly into the mid 90's. That's why I have generally tried to stick with 15-40 Delo. The stroker has been running pretty hot (see cooling thread), so I thought the synthetic might help with the temps. Sounds like for my app, 15-40 or 50 Synthetic might be the best bet........

CRASH
 
Andy, I decided to run 5-40 in mine, synthetic. Figured it was the best combination of good lube at start up and enough lube when warm. I like using the synthetic because it gives me a little more room with oil changes since I don't put that many miles on it and it sits a lot. The newer engine designs in late model vehicles, especially the new generation motors from the big three, run tighter clearances than the older design motors, so the factory recommends a little thinner viscosity oil for those motors. My opinion, anyway, from working for 25 years in dealerships

BTW, you don't want a dealership to put that 0-30 or 5-30 in your older, higher mileage engine, it may get a little noisy. Been there, done that, and had to handle the complaint.
 
Correction.......

I used Mobile 1 0-40....just went and checked. I have great oil pressure on start up, over 60 lbs, so the 0 weight must be OK.
 
I'm using 0W-40 Mobil 1 now that's it's cold here in the winter (55*F day, 35*F night). When summer approaches I'll change it to 15W-50 or whatever thicker grade of Mobil 1 I can find. In the middle of summer it's 115*F day, 95*F night.
___________________________
Dino's "Mean Green Machine"
1992 XJ Laredo 4-dr - 4.6L I6 HO Stroker - 180k miles - AX15, NP231, D35c, D30
small.A9DFB5LA1GZW1.jpg

263hp@4900/321lbft@3300-3800, 1/4 mile = [email protected], 0-60 = 5.8secs
Websites - Jeep 4.0 Performance, 4.6L Stroker Build-Up, Dino's Jeep Tricks
 
0w30 is what Red Line Oil gave me - i asked them about the low weight and they said that they would pay for a new engine if my spec was wrong and the oil harmed any part of my engine...

-Ranger
 
I run 5W - 30 synthetic in the stroker year round in RI - 0 to 95 degrees air temp. I have an oil temp guage in the oil pan and the temp runs up to 210 in hot slow speed conditions but that is 20 degrees colder than with the dyno oil - synthetic really works - we always used it in the DRAG cars. Also i have 21000 miles on the stroker now (2 years February) and get 5000 miles without adding between oil changes. I don't know what the oil company is - I buy the full synthetic from Walmart - I know wally doesn't have his own oil wells so its probably Mobil or? - but it works fine.
 
rsalemi said:
I run 5W - 30 synthetic in the stroker year round in RI - 0 to 95 degrees air temp. I have an oil temp guage in the oil pan and the temp runs up to 210 in hot slow speed conditions but that is 20 degrees colder than with the dyno oil - synthetic really works - we always used it in the DRAG cars. Also i have 21000 miles on the stroker now (2 years February) and get 5000 miles without adding between oil changes. I don't know what the oil company is - I buy the full synthetic from Walmart - I know wally doesn't have his own oil wells so its probably Mobil or? - but it works fine.
Click to expand...

On that note does anyone have any info on that? My dad swears that there oil & filters are just as good as any other brand,but I think he is mistaken. I doubt there oil has any detergents, or conditioners in it even though it has the API seal on it, and there filters are not made as well.
 
You all have things to say about Moble 1, but have you herd about AMSOIL. They have a 5w-30 deisel oil, that I have in my Stroker its great oil, I lost some dergees in my motor and picked up some gas mileage. One other thing you will notice if you run this oil your motor will be quiter. If you run a lighter weight oil that oil will get into all the areas in the motor, Also your motor will turn over easeier in winter, and get to places quicker. The thicker the oil the less it gets into the smaller places in the motor.
My buddy has a 12 value Cummings and he runs Delo 1400 15w-40 and its LOUD! This other guy I know has 24 value and he can sneak up on you, both are stright piped. His running AMSOIL and his Pyro, is running cooler. Something to think about.
 
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