Rear differential fluid replacement interval with Amsoil Severe Gear 75W-90

I bought my well cared for 09 Off Road double cab in 2013 with about 46K miles. At 63k miles, I replaced the unknown rear differential fluid with Amsoil Severe Gear 75W-90. I'm now at 93k miles and doing 90k mile maintenance items.


The Toyota scheduled maintenance guide recommends replacing the rear differential fluid at 30k mile intervals for normal driving and at 15k mile intervals for driving while towing. The Amsoil data bulletin for Severe Gear recommends in light truck differentials for normal driving replacing at 100k miles or owner's manual recommendation, whichever is later, and for severe driving replacing every 50k miles or owner's manual recommendation, whichever is later. The Amsoil data bulletin says all bets are off if there is water intrusion, but I don't suspect water intrusion. I certainly have not submerged the rear differential in water.

I can well afford to keep the truck in top condition. I'm not looking to cut any corners. But I don't want to perform unnecessary maintenance either.

What do you think? See any advantage to replacing earlier than Amsoil recommends? I consider my driving in the normal category since I don't drive in dusty or dirty conditions and my only towing is 3,750 pounds no more than 400 miles per year. Should I go 100k – more than three times the owner's manual recommendation – before changing the fluid?

Amsoil Severe Gear Data Bulletin

 

Just for my peace of mind I'd change it with my oil change. Thats how I change my motorcycle fluids. I love the truck just the same.

 

You're likely to get all kinds of opinions. Mine, FWIW, is to follow Amsoil's guidance - change it between 50K and 100K miles, depending on your driving style/conditions. I say this because Toyota's guidance is based on using standard dino oil, which doesn't resist breakdown as well as a good quality synthetic. You're no longer using standard dino oil, so the 30K mile guidance no longer applies. Changing more often won't hurt anything except your wallet, but neither is it of any real benefit.

An exception to this is motor oil, where filter life must also be considered. Unless you pair good quality synthetic oil with a comparable long-life filter, you should change the oil and/or filter no less frequently than the shorter of the two rated lifespans.

 

Personally i'd go with dino oil and manufacturer's recommended changes.

 

Are you saying you change the rear diff fluid EVERY 5000 miles?!

 

No recommendation is 30k

 

I think if you don’t trust the Amsoil to last its recomended 100k intervals you are wasting money on the Amsoil.

Its unnecessary to change it out sooner than what is indicated based on use.

If you are one of those people that likes to tinker and replace fluids then stick with Mobil 1 or something cheap and change every 30k.

 

Boom. Lucas dino 80w-90 is about $6/qt and is great stuff. $36 will do the front diff, xfer case and rear diff. Plus the cost of the drain/fill plug gaskets.

 

I run Amsoil in just about everything including dirt bikes, quads and lawn mowers. I recently used the Severe Gear in my wife's IS350 with the sole intention of running it for 100k. In the truck I only plan on running it for about 60k - 75k depending on how much I tow. I think 30k is way too early for this oil and I wouldn't go 100k in a truck.

 

My 4cyl truck has an open differential and sees 90% light service, the other 10% is fairly hard. I'm running the Amsoil Severe Gear 75w90 and changing it at 60k mile intervals, which is around every 5 years. Probably could go longer but nope.

 

I run Severe Gear. My first interval was 30K. Looked brand new. I may go 60K next go around.

 

There’s a lot of owners that change diffs to synthetic and never change it again. Check out BITOG

 

Switched to Amsoil at 100k. When I pulled the front axles to upgrade to LT at 142k, the oil that came out looked great.

 

Just change it and be done with it for awhile!

 

Words of wisdom

 

Gonna do both diffs, T/C, & M/T in the near future. Gonna use a good synth. Amsoil's one I'm considering.

 

While how long it takes Amsoil Severe Gear to break down is certainly important, one reason I posted this topic is I was wondering if you lose information about the mechanical condition of the differential itself when you move to an oil with a replacement interval longer than recommended in the Toyota owner's manual. I think I read on here somebody noticing metal in the oil they drained out, for instance.

 

Mechanical LSD's might have more crap in the oil from the friction discs deteriorating, which raises another point, LSD additives.

When I swapped over to Amsoil, I also installed Gold Plug, magnetic plugs. I'll know when I do my first change if there's any metal.

What I did notice was that the front diff was milkier. Maybe it had more moisture because it doesn't heat up like the rear? Don't know. Looked fine after 40k this time though.

Water crossings would lower the oil change interval as well. Also towing.

 

There will always be some metal flake in used lube, big pieces are not good though!

 

agreed.....a light dust of metal would not be a concern to me and I would consider that normal wear and tear.

Actual flakes or chunks wpuld be cause for concern to me.