Synthetic oil in the front diff?

[Number21]

I happen to have gotten the gallon of Royal Purple gear lube I need for my 14 bolt rear end for free, I can't believe this stuff cost $18/quart! I'm putting it in the rear mostly for better gas mileage/cooler temperatures.

My front diff needs a fluid change too...D44 I think? I've never had a vehicle with locking hubs before. Since my front wheels are unlocked and freewheeling 99% of the time, is it a complete waste of money to buy some more Royal Purple for the front? I don't do any serious offroading with this thing and rarely use 4WD. Better off just going with the cheap stuff since it's "unhooked" most of the time? Does the front diff even warm up when the front wheels are unlocked?

[Fursphere]

1) Is your t-case still spinning the front diff, even with the front hubs unlocked?

2) not to hijack your thread - but better gas mileage from diff lube???

[Redcap]

Better gas milage? Right.

I think you are wasting your money on that purple crap.

[72chevyk10]

i was under the impression that the synthetic oil in the diffs. would reduce resistance/increase mileage..

[Redcap]

Originally Posted by 72chevyk10

i was under the impression that the synthetic oil in the diffs. would reduce resistance/increase mileage..

Someone fed you a pretty good line of crap.

[LONGHAIR]

The reduction of friction and heat build-up is reason enough. It is worth having in the rear differential. I would put it in a manual transmission too. It does help....now whether it can make a difference in the fuel mileage of a big ol truck? I doubt it.

[Number21]

Originally Posted by Redcap

Better gas milage? Right.

I think you are wasting your money on that purple crap.

I think you are highly uneducated on the subject of oil...and if you didn't read already, I didn't pay a dime for it.

These are some simple facts:
Synthetic oil runs cooler than regular oil. This is through reduced friction. Reduced friction can only equall less energy/gas coming out of the engine. Is it enough to measure in my MPG? Maybe, maybe not, I'm not going to debate that here...but it WILL help. Sorta like pumping your tires up to 50 PSI. You will get better gas mileage that way, that's a fact, but it might not be enough to be measureable in the real world.

Additionally, synthetic oil comes in 75w90, as opposed to the normal 80w90. That means it's thinner cold, increasing gas mileage during warmup. My normal commute is only 7 miles so most of the time my differentials barely get warm, further reducing my particular gas mileage.

Now to put the question more simply - am I correct that in 2WD mode, (NP205) with the hubs unlocked, the front differential should not be spinning when I'm driving?

[72chevyk10]

Originally Posted by Number21

I think you are highly uneducated on the subject of oil...and if you didn't read already, I didn't pay a dime for it.

These are some simple facts:
Synthetic oil runs cooler than regular oil. This is through reduced friction. Reduced friction can only equall less energy/gas coming out of the engine. Is it enough to measure in my MPG? Maybe, maybe not, I'm not going to debate that here...but it WILL help. Sorta like pumping your tires up to 50 PSI. You will get better gas mileage that way, that's a fact, but it might not be enough to be measureable in the real world.

Additionally, synthetic oil comes in 75w90, as opposed to the normal 80w90. That means it's thinner cold, increasing gas mileage during warmup. My normal commute is only 7 miles so most of the time my differentials barely get warm, further reducing my particular gas mileage.

Now to put the question more simply - am I correct that in 2WD mode, (NP205) with the hubs unlocked, the front differential should not be spinning when I'm driving?

correct. nothing should be moving cept the wheels.

[Redcap]

Originally Posted by Number21

I think you are highly uneducated on the subject of oil...and if you didn't read already, I didn't pay a dime for it.

These are some simple facts:
Synthetic oil runs cooler than regular oil. This is through reduced friction. Reduced friction can only equall less energy/gas coming out of the engine. Is it enough to measure in my MPG? Maybe, maybe not, I'm not going to debate that here...but it WILL help. Sorta like pumping your tires up to 50 PSI. You will get better gas mileage that way, that's a fact, but it might not be enough to be measureable in the real world.

Additionally, synthetic oil comes in 75w90, as opposed to the normal 80w90. That means it's thinner cold, increasing gas mileage during warmup. My normal commute is only 7 miles so most of the time my differentials barely get warm, further reducing my particular gas mileage.

Now to put the question more simply - am I correct that in 2WD mode, (NP205) with the hubs unlocked, the front differential should not be spinning when I'm driving?

You are right, I did miss the free part. In that instance, by all means, run the snot out of it!

As far as me being uneducated on oils...not quite the case, I just don't concern myself with a negligible increase in fuel mileage like it may bring.

To your question about the 205, in 2WD mode you are correct.

[Stocker]

Good thread. I remember many years ago as a kid, seeing 4WD Fords drive by in 2WD with their front driveshafts rotating very slowly. Back then part-time with hubs was just about the only thing available, and Fords sat higher so their drivelines were more easily seen. Point is, there may be a small amount of rotation, though probably insignificant. Necessary or not, I have Mobil-1 75W-90 in my front diff too since I was buying it for the rear anyway...