salad

I run Shell Rotella T6 5w40 based on my research. I have not done any UOAs and the idea of promoting longevity through quality lubrication appeals to me.

A lot of people on here swear by the Rotella brand.

The Lucas oil stabilizer is a scam. It does not meet any requirements or specifications (too thick, no certifications). A lot of people see this nonsense marketing about Formula 1 cars and think "hey it must work great if they run it!". About the only thing in common between normal automotive engines and Formula 1 is that they make noise when they use fuel. I've never heard of warming up a Jeep for 20 minutes to get the clearances within spec, dealing with heat from 12k RPM, or rebuilding after each use.

Do you let them warm up the required amount before driving, or typically drive a very long distance? Monograde oils are horrible for urban commutes. If one starts up in the winter and starts pushing the engine to 4k RPM like most dingbats do one would be severely lacking lubrication. Blanket recommendation of something so far beyond the engine's specs without any context is a very bad idea.

XJwonders

I usually drive a minute after starting up the jeep and I never go over 3k rpms.

s346k

i greatly dislike marvel mystery oil. and your last statement kind of refutes its use as a replacement for engine oil.

and I don't know what's so bad about 30 wt oil. there is a better choice for an engine, but it won't kill one like 90 wt or something would. and the difference in lubricating the engine vs a 5w is what maybe .125 seconds at start up? actual time from pump to bearings? and turning 4k on a cold motor is bad no matter how it's sliced. the hard parts need heat to function properly. thinner oil won't save a valvespring.

cropduster

Super Tech 10w-30 HighMileage or Mobil Super 10w-30 and a NAPA Silver or reg. Purolator filter. Runs great,I don't loosen or burn any in 3500-4000 miles.

ShadowWalker

I tend to use the Peak oil. It was always on sale and was deemed a good conventional for older engines at Bobistheoilguy.com.

Unfortunately its discontinued at auto zone. I have enough for a couple more oil changes. I will probably switch to Shell Conventional. Menards has it on sale for $2 a quart pretty often.

I use a Purolator or STP filter, never a Fram.

XJwonders

I use mopar oil filter, 5 bucks from Walmart, instead of 11 bucks at pepboys

salad

The problem with monograde SAE30 oil is that it is extremely thick at cold temperatures. How "cold" cold is really makes the difference.

Check out this page: http://www.kewengineering.co.uk/Auto...#_Toc240461890

The chart is a little confusing, but what's important to take away from it is that the number before the W represents an equivalent SAE grade. Note the differences between even 25W and 5W. It's quite large. A hint lies in the column for minimum kinematic viscosity at 100°C. If you notice the spreads between the 40 and 100 viscosities and extrapolate it down to even lower temperatures (look at the final graph at the bottom of that page), the difference is even more significant.

Here's some sample information I've collected to demonstrate the differences even further:

In the Jeep 4.0, below 0°F a 5W oil is specified by AMC and Chrysler. See above for the viscosity differences. The difference between a 5W and straight oil when cold is tremendous. Based on used oil analyses (bobistheoilguy.com) Xw40 weight oils (Rotella T6 and Delvac 1 ESP) show the least amount of wear (based on iron content). About a decade and a half ago, NA and EU owner's manuals specified 30 and 40-weight multigrade oils alongside each other. Of course with heavier oil you take a hit on fuel economy. European models are now the only ones with the 40s, I believe increasing fuel economy and emissions targets are the reason for the decline of SAE 30 weight oils in passenger cars in North America. (Interesting thing to note is that the 2004 Hyundai Elantra 2.0L has a generic internationalized manual that specifies both types.)

Anyway, despite better wear indicators with heavier oils (SAE 40 multigrades), the lower your startup viscosity (15W30, SAE30, 15W40, 20W50) the less oil your pump can push, resulting in less flow. Consider the valve train in the 4.0: Oil is forced by the pushrods via hydraulic lifters where it is supposed to splash around on the rockers and valves. This is a huge reason why it is important to keep RPMs low until the oil gets warmed up, and likely why so many 4.0s sound like diesels (mine included)

bigbadon

A+ To that guy in Indiana running straight 30, take a peek through your oil fill cap after you start your engine on a cold morning and you will be shocked to see NO oil on the rockers for SEVERAL minutes!!
This is why rocker pivots wear out. Multi-grade is the best of both worlds. If you live in a warm climate or use a engine heater 30 wt may work for you but whats the point?

highmileage

Good read... I'll keep using Penzoil 5W30, Hyperlube in the summer and MMO all year.

XJwonders

I don't know if u was speaking to me but I live in Pennsylvania, and in last few years the air temperature in winters haven't dropped below 20 degrees, and believe me, I have checked under the oil cap after start up, there's still oil flowing around.

And not to mention all other trucks that I have owned, the engines outlasted the bodies, and I ran SAE 30 the whole time. I guess that since nobody else told me otherwise, I continued to use it and didn't have any problems so far.

Salad, I will read your link soon. I'm not saying that SAE 30 is the ultimate and the best way to go. I want to see if there's a better alternative to running SAE 30, and if there is, I would be using it.

Anyone, if u guys would like to add that running SAE 30 isn't ideal, please post it. I would like to hear it and learn more facts.
Who knows. Maybe I ll be convinced to run other grades of oil.

salad

My point is that there's really no reason to run SAE30 in our engines. It's lighter than, say, 15W40, SOMETIMES, but cold weather performance is a total gamble since sub-zero viscosity is never tested. It's hard to find in a good additive package (no idea where to pick up Delo 300 outside of truck stops, even then most use 15W40) and kinda expensive compared to oils that fall within the actual specs.

2KXJJEEP

All ways Valvoline Oil 10w30 and a WIX filter

bigbadon

If that is the case you have defied the physics of viscosity and salad's post....so if in fact this is true straight 30 wt is the way to go but I have my doubts.

Puckrobber

I've used many different brands in my rigs over the years. Kinda impressed with Mobil 5000 in 5w-30 form. Used it in my V8 Tundra for several thousand miles with no noticeable use or breakdown. Just had the "Red Rocker's" oil changed last week. Not sure what brand my mechanic used, except that it's a 5w-30 Synthetic blend. We'll see how it does over time on a 210,000 mile XJ.

Radi

Well nothing except for the lower flow when cold issue. Years ago we all ran straight-weight oils, but time marched on and the change to multigrade with better cold flow characteristics was an improvement. The science as to why is out there.
I'm hard-pressed to tell someone who regularly gets 200K miles on a motor to change what they are doing, lol. Clearly you are maintaining your mechanicals well. But it may make the difference between getting 200K and 350K.