Poor mileage? Try changing the diff fluid (1 Viewer)

[RavenTai]

my new 80 had been getting repeatably poor mileage in the 12-13 range, changed the fluid in the diffs and transfer with Chevron Delo, only the front diff looked bad the others were dark but you could still see light through the drain stream, the front however was very thick and black ran out of the drain slowly, I assume contaminated with Molly grease as I also have some oil coming out of the knuckle seals

I did this about mid tank and that tankful got 14, filled up last night and the first full tank on new diff fluid got just under 15 a nice improvement not sure if Delo has any mileage properties like synthetics do, I think this is just a case of the old fluid being contaminated

after the birf repack next week I will change the front again. Also going to put M1 of the proper weight in the transfer (Delo is not proper spec for X-fer)

 

[Beowulf]

Reoor mileage? Try changing you diff fluid

RavenTai,
Others have reported measurable mileage increases after switching to syn in the xfer.
-B-

 

[ppc]

Reoor mileage? Try changing you diff fluid

What was the weather/temps during these measurements and what type of driving were you doing?

 

[RavenTai]

Reoor mileage? Try changing you diff fluid

-B- good to hear maybe that combined with other fluid changes can squeeze out some more

PPC the weather here has been all over the place sience I bought the cruiser, typical Atlanta spring high in the 40's one day, 80's the next, evenings are typicaly cool sometimes cold

cruiser see's about 2/3 freeway cruise set @ 70-80mph on my 30+ mile almost all freeway commute to work 3 times a week the rest is typical suburban stuff not quite stop and go city but closer

 

[Rookie2]

Poor mileage? Try changing you diff fluid

Hmmm.. I have noticed a drop in gas mileage (to the tune of 12 to 13 mpg) the last couple of months, and now that you mention it, it seems coincides with weeping :'( knuckles. I'm thinking I may have lost an axle seal by overlubing the steering knuckles. Anyways, I too will be undertaking a birf repack in the near future, and will try Delo in the front.

Raventai - what you doing for the 54mm hub nut? If my math is correct, looks like this would match with a 2 1/8" oversized socket.


R2

 

[IdahoDoug]

Reoor mileage? Try changing you diff fluid

Stating an MPG improvement on a single tankful is simply statistically over reaching. Don't get me wrong, I'm sure there's an improvement with the new oil, but interjecting a bit of restraint for science's sake.

DougM

 

[SteveLCetc]

Poor mileage? Try changing you diff fluid

Did that - changed them all to synthetics. It helped some, but in the 70 - 85 mph range it seems like about two miles per gallon per 5 miles per hour average. Driving the 80 is like trying to push a barn through a swimming pool. I actually got over 20 mpg one time, at about 60 mph with a 30 mph tail wind. A strict 75 mph will get me about 15 mpg, depending on the terrain and elevation (with full synthetics, except new Toyota auto tranny fluid).

Doing the math, at $1.50 per gallon that's roughly $20 per hour saved based on difference in arrival times. Plus, these days a dollar saved is two dollars earned...

If I didn't still have my Corolla I'd be selling my Radar detector.

Steve H

 

[RavenTai]

Reoor mileage? Try changing you diff fluid

Rookie2, try it out and let us know what happens, in the mean time pop the fill port and see if you have grease in you gear oil, if you do it will be overfilled, very dark and thick

for the 54mm socket, my neighbor (Trailcarnage on this board) already has it

[quote author=IdahoDoug link=board=2;threadid=12774;start=msg117595#msg117595 date=1078803207]
Stating an MPG improvement on a single tankful is simply statistically over reaching. Don't get me wrong, I'm sure there's an improvement with the new oil, but interjecting a bit of restraint for science's sake.

DougM
[/quote]


you are right one tank full is not a good estimate of how much gain but like you said I do think its shows there there has been an improvement, all of the previous tanks were in the 12-13 range (I have put 1500 mile on it so far) , and in hind site it makes sense on the 80 there is a lot of metal spinning in that gear lube if it is thickened by the grease (grease is oil and a thickener mixed together) it would put considerably more drag on those parts

my previous vehicle got pretty steady mileage except for on long trips and towing, so I guess my driving patterns are pretty stable I have not done anything out of the norm with the cruiser yet, I would not think that there could be that much of a change due to normal variations and than have it go back to 12-13 again but i have been wrong before

 

[Beowulf]

Reoor mileage? Try changing you diff fluid

>> If my math is correct, looks like this would match with a 2 1/8" oversized socket. <<

Yes. You can buy a Blue Point hub socket off the Snap-On truck pretty reasonable. Sears sells a 2-1/8 socket (very HD) for about $22; it's 3/4" drive so you'll likely need an adapter. I think the Blue Point is available in either 1/2" or 3/4" drive.

-B-

 

[SteveLCetc]

Poor mileage? Try changing you diff fluid

[quote author=SteveLCetc link=board=2;threadid=12774;start=msg117603#msg117603 date=1078803592]
Did that - changed them all to synthetics. It helped some, but in the 70 - 85 mph range it seems like about two miles per gallon per 5 miles per hour average. Driving the 80 is like trying to push a barn through a swimming pool. I actually got over 20 mpg one time, at about 60 mph with a 30 mph tail wind. A strict 75 mph will get me about 15 mpg, depending on the terrain and elevation (with full synthetics, except new Toyota auto tranny fluid).

Doing the math, at $1.50 per gallon that's roughly $20 per hour saved based on difference in arrival times. Plus, these days a dollar saved is two dollars earned...

If I didn't still have my Corolla I'd be selling my Radar detector.

Steve H


[/quote]

MInor correction - I rechecked and it's actually "only" about 1.5 mpg per 5 miles per hour - still, that comes out to $15/$30 per hour.

 

[RavenTai]

Poor mileage? Try changing you diff fluid

ouch that is a big difference with speed might pay to slow down a little but here in ATL I'll get rear ended if I try to do the speed limit, my 2500HD was the same way my best tank was towing an armored Tacoma, the trailer was a POS and I had to drive 55 all the way from Tennessee, even towing that load the slow sped beat all other tanks by a considerable margin

 

[otis22]

Reoor mileage? Try changing you diff fluid

I have changed out the front diff and trnsf case fluids out, but the rear diff filler nut is a mother. I have tried various penetrating oils to no effect. Any suggestions?

 

[landtank]

Poor mileage? Try changing you diff fluid

hand impact

 

[Rookie2]

Reoor mileage? Try changing you diff fluid

[quote author=RavenTai link=board=2;threadid=12774;start=msg117632#msg117632 date=1078806173]
Rookie2, try it out and let us know what happens, in the mean time pop the fill port and see if you have grease in you gear oil, if you do it will be overfilled, very dark and thick
[/quote]

I bought a 24mm last night to do just that. If I pull the plug, should I expect the mixture of gear oil and grease to look something like the birf. soup, maybe a little thinner??

Thanks,
R2

 

[RavenTai]

Reoor mileage? Try changing you diff fluid

[quote author=Rookie2 link=board=2;threadid=12774;start=msg118271#msg118271 date=1078891562] should I expect the mixture of gear oil and grease to look something like the birf. soup, maybe a little thinner??
[/quote]


that is about what the gear oil in the front of mine looked like, thin birf soup, it was very black in that no mater how thin you could not see through it

 

[Rookie2]

Poor mileage? Try changing you diff fluid

[quote author=RavenTai link=board=2;threadid=12774;start=msg117489#msg117489 date=1078792317
changed the fluid in the diffs and transfer with Chevron Delo,

Raventai,

Where did you locate the Delo gear oil? I haven't found it anywhere here yet.

Thanks,
R2

 

[RavenTai]

Poor mileage? Try changing you diff fluid

I got it at a lubrication distributor, it only comes in drums or 5gal buckets since it takes 2 gallons to do all the gear oil sumps in the 80 you go through it pretty quick

to find a Delo distributor try here , give the ones in your area a call and ask for “CHEVRON DELO® GEAR LUBRICANT ESI SAE 80W-90” prices range pretty wide, go to the cheapest/closest

again I am not sure that the Delo by itself has any mileage savings, maybe it does maybe it dosent I don't know, none of its supporters here nor over at BITOG have ever mentioned it either way, I think it is more that the old stuff was contaminated

I picked it because it is about the same cost (per quart) as the regular stuff I can buy locally but has a good reputation for a Dino gear lube, it uses a borate additive instead of the sulfur all other gear lubes use, witch some say is a good thing (above my head), makes it not quite as stinky as normal gear lube (that I can understand) , that and I find the 5gallon bucket with a pump a lot easier to deal with than squeezing quart bottles



more info:

http://library.cbest.chevron.com/lubes/compprd9.nsf/0/71a5fe83e81c311c88256628007d8eb1/$FILE/GL-11.pdf

 

[Rookie2]

Poor mileage? Try changing you diff fluid

Thanks Raventai. I'll look into it.

I dropped the drain plug to be greeted by a sess-pool of septic sluuuuge...right you are Kenny. I pumped it full of Coastal for the mean time, till I can get everything together for a birf job. I pulled the knuckle plugs and it looks like the front portion of the knuckle still has moly grease in tact, but the back sides are soupish.

I'll see what the gas mileage does in the meantime.

Later,
R2

 

[4RUNNERJADE]

Reoor mileage? Try changing you diff fluid

[quote author=otis22 link=board=2;threadid=12774;start=msg118169#msg118169 date=1078881857]
I have changed out the front diff and trnsf case fluids out, but the rear diff filler nut is a mother. I have tried various penetrating oils to no effect. Any suggestions?
[/quote]

DID you ever get that Rear diff fill plug out ?

1.24mm and a 2 foot cheater bar and a 1/2" drive breaker bar.

if that dont work.
2.try alittle heat/torch = last resort thow.

3.at Wall-Mart buy some
"P.B. BLATER "WILL penetrate gosh affull crapp,

carefull thow,If your down wind of it,zit's are you , by the next AM

 

[RavenTai]

Poor mileage? Try changing you diff fluid

second full tank with new gear lube, included a 85MPH mad dash to work this morning (I was almost late) still got 318.5 miles, 21.825 gallons = 14.59 MPG slightly less than the previous but much better than all the pre-gear lube tanks