Gear oil temp ?

[NatersXJ6]

Curious

So you got me curious. I went out and took some ray tech IR readings on my differentials.

People can naysay all they want, IR guns aren't terribly precise, but they are relatively consistent, and thus can detect change relatively well.

My backyard digital thermometer says 98.9. the IR gun on the jeep frame above the rear axle says 101. I drove the jeep about 2 hours ago on the freeway for 1/2 hour. The IR gun on the diff (about 3/4 inch Away at bottom of ring gear) says 112, axle tube 111. two hours cooling time.

My 05 F250 has 116k miles. I bought it at 28 or 29k and have never changed the axle oil. it has definitely been hot, most of the cover paint is peeled away, probably burned, no seal leaks though. I drove it hard in city traffic for 1.25 hours then parked it about 45 min ago. IR on frame says 107. On Diff cover 125-130. On axle tube 118.

I'm not worried about it. I do remain curious though. I'm betting IF, and it is a big IF, you have a problem, I'm betting one or more bearings aren't properly lubed. Probably pinion. Your description of "normal silvery stuff" seems off to me. I don't think I've ever gotten silvery stuff out of an axle.

I'm not trying to feed your paranoia, I wonder if you should seek a professional opinion. The only person who can tell you if your oil has failed is a lab. Buy a sample kit, send a sample to the lab, and do the same thing again in 6 months, try to establish a baseline... Or drive it til it blows apart and then come on here and say "I told you so"!

 

[red EOD veteran]

Contact a oil test company such as Blackstone Labs and send them a oil sample, they will analyze it and let you know if they find something out of the ordinary.

Increasing the fluid capacity does not lower the temps overall. Helps slow down the rise in temps when you are working the truck harder but that's it.

The deeper your gears the faster they are turning and the more friction/heat they build. So with 4.56 gears and probably stock 31" tires you are making the differential spin faster than it wants to at 80mph. Adding extra weight such as the trailers increases this.

Synthetic oils are thinner, great for getting into areas with extremely tight tolerances but they tend to run a little hotter than conventional oils. A pickup truck differential does not have the tight tolerances where synthetics are needed.

If your axle is topped off to the fill hole like it's supposed to be, relax about the temps. You are increasing the temp by driving too fast with the trailer and your gears, but not killing the axle overnight. Looking at probably 100k miles before the axle needs all new bearings instead of 150k miles.

 

[TwinStick]

The factory fill spec is 5/8" below the fill hole, according to my dealer.

Will filling to the fill hole cause issues, if the dealer is correct ?

 

[upsidedown2]

The factory fill spec is 5/8" below the fill hole, according to my dealer.

Will filling to the fill hole cause issues, if the dealer is correct ?

Have not heard that one. Why is the hole not 5/8 lower then? Fill it till it just runs out and be done.

 

[Mo4130]

Perhaps to account for expansion from heat?

 

[pugslyyy]

Have not heard that one. Why is the hole not 5/8 lower then? Fill it till it just runs out and be done.

This. Never heard of filling to below the hole. Every differential, transfer case, gear box that I've ever seen without a sight glass or dipstick you fill until it runs out.

 

[Stumpalump]

Yeah, cause spit is so much more reliable than a thermometer. OK then, seeing as how you think you know everything, what oil should I be running in the rear diff ?

This is what is in there now: https://www.amsoil.com/shop/by-product/gear-lube/75w-90-long-life-synthetic-gear-lube/?code=FGRQT-EA

As far as pics, I did take them. But I have no idea how to post them on here. New phone, technologically impaired & 53 yrs old. My I.T. tech just got a job & moved out so.................

I feel your pain. I'm the same age. Do you use Apple I phone? Posting pics is simple and fast with them. Use your hand on your diff. If you can touch it for a few seconds like a really hot coffee cup then your fine. If you think you will instantly lose skin then it's hot. That's when you spit on it. Slow boil is getting warm. Instant steam and your screewed. You lose a lot of HP thru the diff and that energy is turned to heat. It is what it is. Amsoil makes lube in 4 weights. Piss thin, thin, ok, and good. You put in piss thin so fill it till it pours out of the fill hole and run it. If it's still too hot for you then put in the 250 stuff. Forget the numbers because they never really applied to synthetic oil or lube but are listed to market against conventional oils. The 250 stuff flows better than 75-90 conventional when cold for example.
Don't waste what you put in until you see if the cover and fresh oil helped and are not scalding. Next time you change it buy the 250 in your Amsoil or better yet buy the redline heavy shock proof oil. It's so good any busy race supply or speed shop in your area probably stocks it. It will drop your temps some but your still generating a lot of heat pulling that load.

 

[TwinStick]

Funny you say that. I was watching a SCORE 400 or MINT 400 race on tv last year & one team that had Amsoil stickers all over there vehicle had rear end gear issues. By the end of the race, they determined that the 250 wt gear oil was too thick & that is what was causing the overheating issue. They changed gear oil to the Severe gear 75/110 & problem went away & they finished the race. That was the first time I ever actually witnessed an issue caused by too thick of gear oil. They also commented that to run such a thick gear oil, the lash needs more clearance & therefore the tolerances need to be greater. I am not that knowledgeable on the subject, but it seems to make sense to me.

I will run what is in there now for a year or so but I can almost guarantee that the next oil will be the SG 75/110. It's flash point is 421*F. One grade thicker should do the trick. I will also try different speeds when on trips & keep track. Say, an hour @ 70, pull over & check, an hour @ 65 & check & an hour @ 60 & check. If there are substantial differences, then maybe I need to slow down a little with the 4.56's, or get 35" tires to help off-set the 4.56's. Stock tire size on a Power Wagon is 33" 285/70/17. And, the G-56 manual is geared MUCH lower than the auto. I usually run 5th gear, which is 1.0:1. Maybe I should try running 6th on the flats ? Hemi starts to make good power @ 4000+ rpms. This will be an ongoing thread that I will update periodically. No speed shops that I know of around me. Internet shopping is handy though.

As far as the "silvery stuff" I mentioned earlier: I have gotten the same out of every rear diff & front diff I have ever pulled the cover off of & drained (& that has been quite a few). All 4 of the trucks I have owned (88 Ford Ranger, 2000 Dodge Dakota, 2004 Ram 2500 & my Power Wagon) , not to mention all the people I have done it for on their trucks (I worked with over 400 people & prolly 1/2 owned trucks. Thats is why I said it was normal. If you look at it, you don't see it. If you take your finger & wipe the inside of diff cover, then you will see it. It is so fine, that when you rub it between your fingers, you feel no grit at all, it's just like a fine paste.

Also, I found this: http://www.bestlubeusa.com/gearlube.pdf . It says they recorded rear diff temps of up to 370*F !!! While, yes, that is uber hot, mine were not that hot.

 

[JIMBO]

:sombrero: I have YUKON 5.38 gears in my JKUR and use VALVOLINE 75w-140 fluid

My initial run at 45 mph/20 miles, was 300°F(rear diff.) and that was years ago, now the rear diff avg between 85°F and 110°F for summer runs-

The syn oils will survive high temps(300°), but don't make it a habit !

If your rear diff. is showing 300°F consistently--either the gears are set to tight, or your IR temp gun is wrong-

Whatever

Good luck

:costumed-smiley-007:wings: JIMBO

 

[TwinStick]

Do you tow with it & run 70 mph while towing ? Curious what temps would be towing @ 70 w/5.38's ?

I tow @ 70 because that is the speed limit that most run on the highway. I still get passed on a regular basis @ 70. My dad actually got a ticket once while we were kids for "obstructing traffic" by not going the posted speed limit on the highway going through Chicago/Detroit area.

 

[JIMBO]

:sombrero: No, even though the trailer is light, I don't go over 65mph and usually 60mph in Ca.

Do you tow with it & run 70 mph while towing ? Curious what temps would be towing @ 70 w/5.38's ?

I tow @ 70 because that is the speed limit that most run on the highway. I still get passed on a regular basis @ 70. My dad actually got a ticket once while we were kids for "obstructing traffic" by not going the posted speed limit on the highway going through Chicago/Detroit area.

The rear diff. temp doesn't get over 130°F and will stay under 100°F off-road-

That's the advantage of a careful breakin and using the Valvoline 75w-140 syn, but 5.38 gears is the MAX mechanical advantage available /w the Dana 44, so it's like using the lowest gear in a 26 spd bike--

:costumed-smiley-007:wings: JIMBO

 

[Stumpalump]

Funny you say that. I was watching a SCORE 400 or MINT 400 race on tv last year & one team that had Amsoil stickers all over there vehicle had rear end gear issues. By the end of the race, they determined that the 250 wt gear oil was too thick & that is what was causing the overheating issue. They changed gear oil to the Severe gear 75/110 & problem went away & they finished the race. That was the first time I ever actually witnessed an issue caused by too thick of gear oil. They also commented that to run such a thick gear oil, the lash needs more clearance & therefore the tolerances need to be greater. I am not that knowledgeable on the subject, but it seems to make sense to me.

I will run what is in there now for a year or so but I can almost guarantee that the next oil will be the SG 75/110. It's flash point is 421*F. One grade thicker should do the trick. I will also try different speeds when on trips & keep track. Say, an hour @ 70, pull over & check, an hour @ 65 & check & an hour @ 60 & check. If there are substantial differences, then maybe I need to slow down a little with the 4.56's, or get 35" tires to help off-set the 4.56's. Stock tire size on a Power Wagon is 33" 285/70/17. And, the G-56 manual is geared MUCH lower than the auto. I usually run 5th gear, which is 1.0:1. Maybe I should try running 6th on the flats ? Hemi starts to make good power @ 4000+ rpms. This will be an ongoing thread that I will update periodically. No speed shops that I know of around me. Internet shopping is handy though.

As far as the "silvery stuff" I mentioned earlier: I have gotten the same out of every rear diff & front diff I have ever pulled the cover off of & drained (& that has been quite a few). All 4 of the trucks I have owned (88 Ford Ranger, 2000 Dodge Dakota, 2004 Ram 2500 & my Power Wagon) , not to mention all the people I have done it for on their trucks (I worked with over 400 people & prolly 1/2 owned trucks. Thats is why I said it was normal. If you look at it, you don't see it. If you take your finger & wipe the inside of diff cover, then you will see it. It is so fine, that when you rub it between your fingers, you feel no grit at all, it's just like a fine paste.

Also, I found this: http://www.bestlubeusa.com/gearlube.pdf . It says they recorded rear diff temps of up to 370*F !!! While, yes, that is uber hot, mine were not that hot.

Sans the marketing hype and going by just what I've seen Amsoil does not work. I don't know anybody with racing stuff that would actually use it. A lot of companies sponsor a lot of racers but that does not mean they use their products. I know dirt bike guys that get sponsored by lube companies and they get $1000 worth of product. It may be a chain lube company and they run the stickers but they order cleaning products and jerseys with the budget then put Tri-Flow on the chain. Amsoils problem is it skimps on additives. That's why it won't pass certification. Additives are not oil so they increase friction and hurt milage. Take out the important additives and its simple to prove its better under certain conditions. In the real world you need the additives to flow, harden the metal, reduce corotion, stick to metal parts and hold dirt. Don't buy Amsoil because it does not contain the most important stuff. They are too cheap to buy it so all you are getting is the same base stock synthetic the rest buy without the expensive additives. It's junk.

 

[Buliwyf]

I change about 1000 gallons of oil per year, with far too many samples sent to Cat or other labs. (I hate taking samples) Amsoil is the best we've seen yet. The additives are there. If they weren't, you'd see nothing but foam every time you pulled the dipstick. Not to mention the obvious rust problems. Every Ducati I know of is running Amsoil. And I can't think of an engine harder on oil than those. I haven't seen an Amsoil oil related failure in 20 years of wrenching. Not even a hint of it, in everything from a Superquadro, to a Cummins QSX, to a 20 cylinder MTU 4000, to a Stihl chainsaw.

Not sure where you heard about "no additives". Maybe Amsoil doesn't call them additives, because they truly aren't. You can't have modern oil at all, without the additives. Anti foaming, anti corrosion, anti acid etc. etc. It's the PH additives that wear off and pretty much signal the end of the oils life. Assuming that shear strength is good still, which it always is, in non-race engines.

Their 2 stroke oil is good as well, even though I'm not sure if it has castor in it. I've tested that to failure plenty of times.

Amsoil Dominator 20w50 is the best oil I've used yet. But it's kinda cheating, as it'll eat the cats on street machines. Phosphorous and Zinc additives do that, but they're great for high performance lubes. Complete lack of anti-corrosion inhibitors with the Dominator though. Another reason it's a race oil only. Maybe that's the one you were thinking of?

Amsoil 10W30 Dominator Racing Oil synthetic lab test
Silicon = 3 ppm (anti-foaming agent in new oil, but in used oil, certain gasket materials and dirt can also add to this number)
Boron = 15 ppm (detergent/dispersant, anti-deposit buildup/anti-sludge)
Magnesium = 10 ppm (detergent/dispersant, anti-deposit buildup/anti-sludge)
Calcium = 1661 ppm (detergent/dispersant, anti-deposit buildup/anti-sludge)
Barium = 0 ppm (detergent/dispersant, anti-deposit buildup/anti-sludge)
Zinc = 1613 ppm (anti-wear)
Phos = 1394 ppm (anti-wear)
Moly = 0 ppm (anti-wear)
Potassium = 4 ppm (anti-freeze corrosion inhibitor)
Sodium = 0 ppm (anti-freeze corrosion inhibitor)
TBN = 6.5 (Total Base Number) This is an acid neutralizer to prevent corrosion. Most gasoline engine motor oils start with TBN around 8 or 9.
Viscosity (cSt at 100*C) = 11.6 (cSt range for SAE 30 is 9.3 to 12.4) And cSt (centistokes) in general terms, represents an oil's thickness.

API certification is mediocrity. There isn't a single race car engineer testing API certified oil in his engines anywhere. When the EPA, and multiuse of the oil, are required for the cert, then it's no longer specialized for the task at hand. The 15w50 in my Panigale doesn't need to meet Honda minivan standards.

That being said, the OP doesn't need synth diff fluid. I recommend standard diff fluids because they work fine and are cheaper. I go off road, where there's mud and water. That requires changing the fluid often to check/remove any water. And still, 300 degrees won't even heat my lunch up today.

 

[Inyo_man]

I change about 1000 gallons of oil per year, with far too many samples sent to Cat or other labs. (I hate taking samples) Amsoil is the best we've seen yet. The additives are there. If they weren't, you'd see nothing but foam every time you pulled the dipstick. Not to mention the obvious rust problems. Every Ducati I know of is running Amsoil. And I can't think of an engine harder on oil than those. I haven't seen an Amsoil oil related failure in 20 years of wrenching. Not even a hint of it, in everything from a Superquadro, to a Cummins QSX, to a 20 cylinder MTU 4000, to a Stihl chainsaw.

Not sure where you heard about "no additives". Maybe Amsoil doesn't call them additives, because they truly aren't. You can't have modern oil at all, without the additives. Anti foaming, anti corrosion, anti acid etc. etc. It's the PH additives that wear off and pretty much signal the end of the oils life. Assuming that shear strength is good still, which it always is, in non-race engines.

Their 2 stroke oil is good as well, even though I'm not sure if it has castor in it. I've tested that to failure plenty of times.

Amsoil Dominator 20w50 is the best oil I've used yet. But it's kinda cheating, as it'll eat the cats on street machines. Phosphorous and Zinc additives do that, but they're great for high performance lubes. Complete lack of anti-corrosion inhibitors with the Dominator though. Another reason it's a race oil only. Maybe that's the one you were thinking of?

Amsoil 10W30 Dominator Racing Oil synthetic lab test
Silicon = 3 ppm (anti-foaming agent in new oil, but in used oil, certain gasket materials and dirt can also add to this number)
Boron = 15 ppm (detergent/dispersant, anti-deposit buildup/anti-sludge)
Magnesium = 10 ppm (detergent/dispersant, anti-deposit buildup/anti-sludge)
Calcium = 1661 ppm (detergent/dispersant, anti-deposit buildup/anti-sludge)
Barium = 0 ppm (detergent/dispersant, anti-deposit buildup/anti-sludge)
Zinc = 1613 ppm (anti-wear)
Phos = 1394 ppm (anti-wear)
Moly = 0 ppm (anti-wear)
Potassium = 4 ppm (anti-freeze corrosion inhibitor)
Sodium = 0 ppm (anti-freeze corrosion inhibitor)
TBN = 6.5 (Total Base Number) This is an acid neutralizer to prevent corrosion. Most gasoline engine motor oils start with TBN around 8 or 9.
Viscosity (cSt at 100*C) = 11.6 (cSt range for SAE 30 is 9.3 to 12.4) And cSt (centistokes) in general terms, represents an oil's thickness.

API certification is mediocrity. There isn't a single race car engineer testing API certified oil in his engines anywhere. When the EPA, and multiuse of the oil, are required for the cert, then it's no longer specialized for the task at hand. The 15w50 in my Panigale doesn't need to meet Honda minivan standards.

That being said, the OP doesn't need synth diff fluid. I recommend standard diff fluids because they work fine and are cheaper. I go off road, where there's mud and water. That requires changing the fluid often to check/remove any water. And still, 300 degrees won't even heat my lunch up today.

Excellent synopsis.

 

[Stumpalump]

Two stroke Amsoil does not burn complete. Instead it sticks to your pipe. Pull the pipe off and you can feel the weight. It's either an oily mess or full of thick carbon goo. You can't clean them so you replace the pipe. It's so bad that they tell you to run it at 100:1. Part of what makes power in a two stroke is the oil. Oil has a higher energy level or BTU when it burns. It's why 16:1 oil ratio produces the most power in a two stroke. So unless you direct inject the stuff right on the crank like a modern outboard Amsoil again is junk. In a perfect world their stuff is good. Perfect in a Ducati because like a Ferrari owner they are finicky machines with finicky owners that will change oil after a weekend. I would too if that quackery pyramid sceme oil that refuses to be certified was in my bike. One bottle may be good and the next.....? Is that why different bottles from different cases have different color oil? Certification says you can trust what's in it from bottle to bottle. Why is Amway/Amsoil scared to do that? You can't trust them is the bottom line. The next time you hear of a weird part letting go that destroys a transmission, diff, bike or transaxle look to see how often it's Amsoil. Pistons look fine but some weird intermediate camshaft or tranny syncro bushing shatters and eats everthing. That can happen with any oil but it seems all too often when you hear of a really oddball part letting go it's been run on Amsoil. Steer clear.