Help with Manual transmission and differential oil.

Hello,

I know this has been asked in the forum a lot, but I was wondering if people are running the same oil on their manual transmission and on their differential.

I just bought a 1998 with 137K miles and want to change all fluids, the truck will be used a few times a month moving things around the city.

Specs call for 2.3 qt on the transmission and 1.2 qt on the diff. Both specify Gl-5 on the specs.

I ask because If I buy different oils I'll end up with two different bottles with alot of oil in them, where if one oil is used I'll have half a qt left.

Amazon has the Royal purple for $15

$21 Royal Purple 01300 Max Gear 75W-90 High Performance Synthetic Automotive Gear Oil , 1 Quart (32 Ounces)

http://www.amazon.com/Royal-Purple-Performance-Synthetic-Automotive/dp/B0007QGT34

They don't have amsoil.

Should I just spend the extra ~$15 and run different oils?

MT-90 is about $17

Are these prices good compared to local stores?

Thanks a lot.

What do you do with the extra gear oil?

 

Royal Purple sucks IMO. I had a horrible experience with it and my transmission has never felt perfect since I used it.

I switch to MT-90 for my transmission and it's worlds better.

 

I use the amsoil severe gear 75-w90 in both diffs and the tranny. You will be fine using it in both.

 

Thanks for the advice so far (good to know about RP),

My only issue with amsoil is availability, website lists dealers across the city from me.

Any advice as far as price? how much is amsoil? compared to the other products I mentioned?

 

Just .02 but i use Castrol SynGear. Readily avail and been around for awhile. Yes it is GL5 rated. As long as you keep up with the changing intervals i wouldn't put to much thought into it.

If you are like me and wanted to remove some of the notchiness from it you can use Redline but i didn't feel any difference between it and SynGear.

 

Thanks, I'll order the 3qt of MT-90 from Amazon, then get something else for the differential.

 

+1 for Amsoil Severe Gear.

If you can't locate a nearby dealer, become a Preferred Customer. Doing so costs as little as $10 and gets you a 25% discount on purchases. Note that buying in case-quantity makes shipping somewhat more cost-effective.

 

I love Roral Purple

 

I just now put in Mobil 1 into my t-case and tranny, and plan on using the same for my diffs. Makes it easier to just have that one oil to deal with. AutoZone carries in on the shelf.

 

AutoZone loves it too - they want $21 a qt for it!! That's the

$28 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90. Much cheaper on Amazon.

 

Be careful with the products with the GL-5 specifications. The manual transmission has metals in it that can be broken down by some of the additives used to meet the GL-5 spec.

Pretty sure you owners manual states to only use GL-4 spec'd gear oil in the trans. The Redline MT-90 is a GL-4 oil.

 

I am doing the same and agree. That's what amsoil recommends.

 

My '97 2.7L manual states GL-4 or GL-5. I wonder if the trannies are that different between his '98 2.4L and mine. 2wd vs. 4wd maybe?

 

I was just going over this yesterday with 97tacoNM and took this picture of my manual:



I have read too not to use GL-5, but am beginning to question where that idea comes from in the first place.

FWIW: I ran whatever cheap (think it was Valvoline)

$28 75w-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75w-90 GL-5 in both diffs, transfer case, and transmission for over a year. Had no issues. Late this summer I swapped the transmission out to MT-90, it may have made a little difference, but not really a ton. At least not enough for me to notice any big improvement or anything else to justify the price.

 

I run whatever Toyota has been putting in for the past 12 years. Runs just fine.

 

Interesting. Toyota may have changed it with the newer Tacomas. I got my info from my '98 owners manual. I could be wrong about the metals part or perhaps the newer models use alloys that are more resistant to the GL-5 additives. From what I recall reading (TTORA I think) is that it was the brass syncros that were effected.

 

to clarify my 98 manual also states "GL-4 or GL-5".

I've read that some of the "fancy" GL-5 might actually be too slippery to be used in the transmission because the synchros do not slow down fast enough for smooth shifting....or something like that.

from Red line website http://www.redlineoil.com/Products.aspx?pcid=7
"Since most GL-5 gear oils for differentials are too slippery for manual transmissions, Red Line offers these products that ensure proper shifting while providing ultimate wear protection"

"Appropriate coefficient of friction for most manual transmission synchronizers (other's synthetic gear oils are often too slippery for proper synchro engagement)"

 

I know you have a first gen, but my .02

I've felt a world of difference using redline mt-90. Very happy with it. People on here talk very fondly of it as well.

 

Allegedly, sulphur additives in GL-5 would eat up bronze and other "yellow" metal synchros. I'm sure, in a chemistry class somewhere, an experiment has been run where someone dissolved copper using sulphur and made copper sulfide.

Perusing forums regarding this subject, nothing but hearsay and speculation. "A friend of a friend said..." "My tranny hated it." "When I was a kid, we used GL-4 and our trannies loved it." "The sulphur in GL-5 eats copper alloys for breakfast and then comes back for seconds. Nom. Nom. Nom." "I watched an 'Alien' movie and it bled GL-5 and it ate right through the copper hull of the spaceship."

I have not experienced nor do I know of anyone that has had to do a rebuild because sulphur ate their synchros. Every shifting issues I can recall reading on this forum was solved with a new clutch or new hydraulics.

Snopes.com is curiously silent on the matter...

 

Hmm, I was just wondering about all this myself. I think I'll just buy some Amsoil Severe Gear

$28 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90 and see how it feels. Anything should be better than 183,000 mi gear oil anyway. Good luck OP!