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11-10-2010, 07:14 AM | #1 |
Registered User
Join Date: Aug 2009
Location: Oregon
Posts: 611
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Synthetic oil in the front diff?
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?
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'73 K20 Cheyenne Super Camper Special 350/TH350/NP205 sittin' on 33's. You can set my truck on fire and roll it down a hill, and I still wouldn't trade it for a Coupe de Ville. |
11-10-2010, 09:34 AM | #2 |
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Join Date: Nov 2009
Location: Rancho Cordova, CA
Posts: 54
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Re: Synthetic oil in the front diff?
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???
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1966 C10 Panel (3/4 Ton 4x4 Conversion) 2001 K1500 Silverado Last edited by Fursphere; 11-10-2010 at 09:36 AM. |
11-10-2010, 04:03 PM | #3 |
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Join Date: May 2010
Location: Lewis County, WA
Posts: 1,523
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Re: Synthetic oil in the front diff?
Better gas milage? Right.
I think you are wasting your money on that purple crap. |
11-10-2010, 04:41 PM | #4 |
I built it
Join Date: Sep 2008
Location: Bakersfield ca
Posts: 744
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Re: Synthetic oil in the front diff?
i was under the impression that the synthetic oil in the diffs. would reduce resistance/increase mileage..
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'72 k10 lwb 454, th400, 205, d44ft, 12b rear, 4in skyjacker, 35x12.5-15 superswampers, 4.56, blazer tank. painless wiring harness '98 dodge 3500 12v 5sp 4x4. the truck that actually runs |
11-10-2010, 04:55 PM | #5 |
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Join Date: May 2010
Location: Lewis County, WA
Posts: 1,523
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Re: Synthetic oil in the front diff?
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11-10-2010, 06:49 PM | #6 | |
just can't cover up my redneck
Join Date: May 2004
Location: Columbus OH
Posts: 11,414
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Re: Synthetic oil in the front diff?
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.
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11-10-2010, 10:51 PM | #7 | |
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Join Date: Aug 2009
Location: Oregon
Posts: 611
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Re: Synthetic oil in the front diff?
Quote:
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?
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'73 K20 Cheyenne Super Camper Special 350/TH350/NP205 sittin' on 33's. You can set my truck on fire and roll it down a hill, and I still wouldn't trade it for a Coupe de Ville. |
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11-10-2010, 10:56 PM | #8 | |
I built it
Join Date: Sep 2008
Location: Bakersfield ca
Posts: 744
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Re: Synthetic oil in the front diff?
Quote:
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'72 k10 lwb 454, th400, 205, d44ft, 12b rear, 4in skyjacker, 35x12.5-15 superswampers, 4.56, blazer tank. painless wiring harness '98 dodge 3500 12v 5sp 4x4. the truck that actually runs |
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11-11-2010, 12:48 AM | #9 | |
Registered User
Join Date: May 2010
Location: Lewis County, WA
Posts: 1,523
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Re: Synthetic oil in the front diff?
Quote:
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. |
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11-11-2010, 02:25 AM | #10 |
20' Daredevil (Ret)
Join Date: May 2003
Location: Jefferson State
Posts: 13,688
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Re: Synthetic oil in the front diff?
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...
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