Originally Posted By: southernjeeper
Originally Posted By: 440Magnum
Originally Posted By: southernjeeper
Originally Posted By: yonyon
The thicker the oil is, the more energy lost to friction from pumping it. Of course, if your engine is worn to the point that the piston rings are like the goggles (they do nothing) then you might get better fuel economy using the Lucas stuff.
This is the sole reason I wanted to purchase and use the Lucas. I have over 200,000 miles now and that is why I wanted to stay away from any 'upper' engine work ie rings, valve train, etc.
What gets me thinking is how some of you say --why in the world am I putting something like Lucas in the engine and use a high mileage oil--. So now my dilemma is a toss up.
Should I switch over to a thicker oil like 15w40 OR stay with the Valvoline Maxlife without the Lucas and just use some other oil additive??? I want to stay away from valve train/ring work til the engine goes kaput. Then I will really have fun with the options I can go with when that time comes.
4.0HO
AW4
NP231 tcase
8.25"
2" rusty's coils
1" daystar extended shackles & regular HD rear springs -rear-
not bad for 233,600 some odd miles
Even if your 4.0 had 400,000 miles, if its not burning oil and sustains good oil pressure there is ZERO need for special oil or additives. That said, MaxLife is a very good oil and you'd be fine to stick with it. Personally, I favor Rotella t6 4w40 in my 4.0s, but that's just me. You'd be fine on Pennzoil Yellow Bottle 5w30 if you wanted to go that way.
My biggest gripe with Lucas "stabilizer" is that not only does it have no antiwear additives, there is evidence that it increases oil foaming.
Just curious, what are your miles on those two jeeps of yours? If you are saying you are really happy with running a superb oil like T6 that is that low of viscosity 4w40. Isn't that ---answer this dumb question of mine -- It means that at 'start ups' the oil is like a 5 weight yet when it warms up its like 40 weight? Sorry for the dumbest oil question but is that correct?
I run straight 30 weight in the willys so would that mean instead of going to that extreme of running SAE30 in the cherokee the 4w40 T6 is the cat's meow for the 4.0's?
I'm fine with giving that a shot with Rotella. Though this time it will be 4w40 if what I asked above made sense.
Thanks 440magnum. That was helpful advice.
edit.
Is it 5w40 you mean?
Hope I get all your questions here:
The 99 has just over 150k miles, the 01 has 95k. I also have run T6 in Mopar v8s with over 200k.
As for the 5w40, yes that is what I use (I think its still the only forumlation that T6 comes in) Don't be fooled by that "5w", it doesn't mean what most people think it means ;-) The SECOND number (after the w) is intended to represent the operating temperature weight of the oil. So once the engine is warmed up, a 10w40 is the same as a 5w40 is the same as a 0w40. Of course there is some variation brand-to-brand, BUT they all fall into the allowed range for a 40 viscosity oil. The first number is an attempt to show the stability of the oil. I find it useful to look at it by starting with all oils at OPERATING temp and thinking about what happens as you cool them, rather than thinking about room temperature and thinking about warming them up. For example, it you take a typical 10w40 oil and cool it down from operating temperature, it will thicken along a certain temp-vs-thickness curve. If you take a 5w40 and cool it, it will thicken LESS than 10w40 (tend to stay the same thickness). A 0w40 will thicken even less as it cools. So, running 5w40 means that my engine is still getting a thicker oil at operating temp than it would with a 10w30, and also getting better flow when its cold. An ideal oil wouldn't change thickness at all with temperature, but in reality all oils are thinner hot than they are cold. But the ones with the wide XXwYY range thicken less as you cool them.
The downside to wide ranges is that sometimes "viscosity index improvers" are used to get the wide range. They are essentially plastic-like polymers that stabilize the thickness of the oil, but they can contribute to sludge. A kinda-general rule is that the thicker the number after the w, the heavier base stock the blender can start with and so the easier it is to get a wide range without to many VIIs (although they sometimes start using "pour point depressants.) So in that way, a 5w40 might be easier to get than a 5w20. Most name-brand synthetic and semi-synthetic oils get to 5w40 ratings without too much use of VI improvers. But that's why you tend to only see pure synths in the wide range ratings, and only synths and semi-synths in the Xw20 ranges, especially 0w20.
