front/rear diff's & xfer case oil

[firebirdguy]

about to change the oil in the diff's & transfer case on my 08 4wd & was wondering what type of oil y'all prefer to use, synthetic or conventional? & is it best to follow the weights in the owners manual of 75/90 front & xfer case & 90w rear?

the reason i ask is because in the muscle car & high power/racing world most guys use conventional in the diff due to high stress & better shear strength compared to synthetics. in fact, many companies that make aftermarket diffs & gears specifically state to NOT use synthetic gear oils in racing or heavy towing applications.

just curious what the best oil is for the 4runners. i dont plan to do any heavy off roading or towing. i realize synthetics will flow better when cold & may provide a slight increase in MPG... just dont want to hurt anything.

 

[Swipter]

2015 TOYOTA 4-RUNNER (4.0L 6 -cyl Engine Code 1GR-FE 0) Motor Oil, Filters and Lubricants - AMSOIL

This is easy to use for the diffs and meets standards. You can get a discount if you do the 6 month dealer thing. It's worth it. I have two 4runners so I got enough for both. Maybe only one 4runner, the dealer thing doesn't pay off.

 

[mikewhiskey]

about to change the oil in the diff's & transfer case on my 08 4wd & was wondering what type of oil y'all prefer to use, synthetic or conventional? & is it best to follow the weights in the owners manual of 75/90 front & xfer case & 90w rear?

the reason i ask is because in the muscle car & high power/racing world most guys use conventional in the diff due to high stress & better shear strength compared to synthetics. in fact, many companies that make aftermarket diffs & gears specifically state to NOT use synthetic gear oils in racing or heavy towing applications.

just curious what the best oil is for the 4runners. i dont plan to do any heavy off roading or towing. i realize synthetics will flow better when cold & may provide a slight increase in MPG... just dont want to hurt anything.

I thought it was the other way around- that synthetics have better shear strength and break down slower than conventional.

 

[ZebRuaj]

Any 75w90 flavor of your choice.

I've used Valvoline 80w90, Valvoline Synpower 75w-90, and currently M1 75w90.

Change it out more often if you do water crossings.

 

[firebirdguy]

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I thought it was the other way around- that synthetics have better shear strength and break down slower than conventional.

for motor oil that may be true... but for heavy weight gear lubes, synthetics are "thinner" by nature due to better cold pour & flow properties than conventional. big name companies like eaton, auburn, richmond etc specifically say to not use sythetics in high horsepower race or heavy tow applications for most their diffs & gears. i have a 500+ horse power firebird i drag race with an eaton center section & yukon brand gears & they both say not to use synthetics.

i know the 4th gen v6 4runners aren't considered high power & i dont plan to do any heavy towing or off roading, just wanted to hear others suggestions & experiences with what type of oils they use. & amsoil may be good oil but way too overpriced for me & what this 4runner will be doing. valvoline synthetic or conventional is plenty good to replace stock fluids.

is it best to stick with 90 weight in the rear or is an 80/90 ok? i live in the midwest so no extreme hot temps & figured maybe the multi viscosity might help a little in the winter? but i will probably just stick with the weight toyota says to use.

 

[rdruss]

In an extensive gear lube test of 14 popular brands from 2007 that was posted on this website, Amsoil Severe Gear 75w90 was the clear winner.
Followed by: Mobil1 75W90, GM Syn Axle 75W90, Castrol Syn 75W90, Redline Syn 75W90, Pennzoil Syn75W90, Valvoline Syn 75W90.

Royal Purple and Lucas were in the bottom three.

You pick what you like. I've been using Valvoline and Mobil 1 in my '03 V8, will lean more toward Mobil 1 and Amsoil in future.

 

[firebirdguy]

ok, so sounds like many are using a synthetic gear oil with no real issues to speak of. i will go with a synthetic of the specified weight.

thanks!

 

[hinmo24t]

sounds like you may be a step ahead of the others, considering how many people change these fluids...wonder if youre onto something despite this sample

 

[eleven14]

ok, so sounds like many are using a synthetic gear oil with no real issues to speak of. i will go with a synthetic of the specified weight.

thanks!

I changed mine at 100k (2008, v6) and used Toyota spec'd fluids and saw an automatic 2+ mpg jump. Curious what you'll see with synthetic and also what your current mileage is?

 

[firebirdguy]

I changed mine at 100k (2008, v6) and used Toyota spec'd fluids and saw an automatic 2+ mpg jump. Curious what you'll see with synthetic and also what your current mileage is?

WOW! 2mpg from just changing diff & T-case fluids with non synthetic? thats pretty impressive.

mine is an 08 sport v6 4wd at 140k miles i just bought a couple months ago. very limited service history on it so im pretty sure these fluids were never changed... along with transmission, radiator & power steering.

so i plan to do a complete fluid change on it ASAP & will use synthetics for diffs & T-case. dex2/3 for PS, & debating on maxlife for trans over WS.

 

[eleven14]

WOW! 2mpg from just changing diff & T-case fluids with non synthetic? thats pretty impressive.

mine is an 08 sport v6 4wd at 140k miles i just bought a couple months ago. very limited service history on it so im pretty sure these fluids were never changed... along with transmission, radiator & power steering.

so i plan to do a complete fluid change on it ASAP & will use synthetics for diffs & T-case. dex2/3 for PS, & debating on maxlife for trans over WS.

Yea I was shocked. And also 95% sure that they were original fluids. Also swapped transmission (WS) and coolant (toyota spec) with no significant differences or issues. Next is brake fluid and PS for me.

 

[smyles1632]

 

[Terminator03]

When I changed mine a month or two ago, I used Mobil 1 in the rear, but couldn’t get the plug out of the front, so while I was waiting for a new plug, did some research and that Supertech did really well in testing, and even better than some of the major brands. So, I bought enough Supertech to do the transfer case and front diff.

OP, don’t forget to order some new seal washers for all 3. They are cheap, and I found a set of them on Amazon. I also ordered my replacement front diff plug from there once I had the part number from another thread. I ended up beating it up pretty bad with a chisel trying to shock it loose, but ultimately it was a mapp gas torch that broke it free. That’s why I ordered a new one in anticipation of wrecking the original.

 

[firebirdguy]

yes all supertech oils are very good. proven by numerous oil analysis done at bobistheoilguy. like you said, its even better than or equal to lots of big name brands. for the price, supertech really cant be beat.

i plan to get new crush washers when i do the fluid changes, but have had good luck re-using the old ones on other vehicles if they are in good shape & only been removed 1 time.

still curious on the rear diff oil weight... manual says above 0F 90weight & below 0F 80/90... i live in the midwest & during winter season it gets below 0 quite a bit, so is 80/90 ok to use year round since when its warmed up its a 90 weight oil anyways??

 

[Terminator03]

yes all supertech oils are very good. proven by numerous oil analysis done at bobistheoilguy. like you said, its even better than or equal to lots of big name brands. for the price, supertech really cant be beat.

i plan to get new crush washers when i do the fluid changes, but have had good luck re-using the old ones on other vehicles if they are in good shape & only been removed 1 time.

still curious on the rear diff oil weight... manual says above 0F 90weight & below 0F 80/90... i live in the midwest & during winter season it gets below 0 quite a bit, so is 80/90 ok to use year round since when its warmed up its a 90 weight oil anyways??

Not sure for your region, but I felt comfortable using the M1 75/90w for the northeast.

 

[firebirdguy]

im in iowa, we get some pretty bad winters, this winter we set records with -31f temps & lots of 0 & -5 to -10 degrees for a week or more straight, but i rarely drive when its that cold.

the front diff & t-case call for 75/90 regardless of temp, but the rear says 90 if above 0f & 80/90 for below 0f... so im ok with running an 80/90 since it will see 0f temps occasionally. if i lived in florida or az etc i would run the straight 90... & i'd be a much happier guy not dealing with the stupid cold winter temps & salted roads!!!