Gear oil 85W140 vs 75W140 thickness

[aquariuscsm]

Is there much difference in cold temperature thickness between a synth 75W140 vs 85W140 GL5 gear oil? Just a lil curious. The rear diff in my car specs an 80W90,and I was just curious about the difference between those two weight.

 

[D-Roc]

Go to Wally and shake a bottle of 85W140...even at room temp its thick. 75W140 is synthetic, and usually has pretty good cold flow properties.

 

[dnewton3]

True, to a point. You can also compare the cold temp properties by either checking the PDS for the desired products, or checking out the viscosity chart at this website.

(Caution - I'm going to make some assumptions here based upon the OP's signature and area.)
But in the OP's South Texas region, I don't know that such a thick product is even warranted, unless some heaving towing is taking place all the time, (which I doubt, given the vehicle in his signature).

I'd think that either 80w-90 conventional or 75w-90 synthetic would be most appropriate for his application. The Amsoil Severe Gear 75w-90 would perhaps be a good choice, given his apparent preference towards high-end products. Or, if he's just dead set on going thicker (perhaps he's racing?), then maybe the Severe Gear in 75w-110?

 

[Johnny]

For some comparisons, here are three of Amsoil's products, all synthetic.

Severe Gear 75W-90
40c vis 109.01, pour point -58

Severe Gear 75W-140
40c vis 194.3, pour point -54

80W-90 (what your using)
40c vis 116, pour point -43.6

Pennzoil conventional 80W-140
40c vis 247.6, pour point -38

 

[Johnny]

The Pennzoil I posted above is a blend. Here is their 85W-140 conventional. Big difference.

40c vis 352, pour point 5 degrees.

 

[D-Roc]

Originally Posted By: Johnny
The Pennzoil I posted above is a blend. Here is their 85W-140 conventional. Big difference.

40c vis 352, pour point 5 degrees.


Like molassess

...I thought that pour point was off...80W140's are usually syn.

 

[kickinit]

NuBee here. It has been suggested to me to run Pennzoil Synchromesh in the transmission & rear diff. of my 96 miata. Owner,s manual says API GL 4-5 for trans & GL-5 for rear. Found out that the Pennz has no API GL rating. Is someone trying to pull my Yittle Yegg or what?

 

[aquariuscsm]

I think ATF`s and synchromesh fluids are all GL4 rated,right? I read here,I believe,that Miata manual trannies spec a 75W90 GL4. Have you tried Amsoil MTG yet? I wouldn`t think you`d want to put a synchromesh fluid in the rear diff either. I know my car`s rear diff specs an 80W90 GL5 with no limited slip required.

 

[kickinit]

I am on board with that. I've ordered 3 qts. of MTG 75-90 for trans. & 1 qt. of severe gear 75-90 for the diff.. Question arose because this is the advice given by a Miata guru but checking the owners manual set off my inner alarm bell. Pennzoil site describes the great attributes of synchromesh but assigns no Gear load factor or viscosity numbers to this product while doing so with all of it's other Gear oil product descriptions. I posted hoping an oilhead knew why this stuff would would be used & recommended by a garage that specializes in Miatas. Thanks for the reply. I am waiting for my Amsoil.

 

[Johnny]

The Pennzoil Synchromesh is about a 75W-85 and it does carry a GL4 rating, and would probably work pretty good in your transmission. Anyone that would recommend you put it in the rear differential should be taken out and shot.

 

[D-Roc]

Originally Posted By: Johnny
The Pennzoil Synchromesh is about a 75W-85 and it does carry a GL4 rating, and would probably work pretty good. in your transmission. Anyone that would recommend you put it in the rear differential should be taken out and shot.


You forgot to add to the above...peed on and dragged through the streets, Johnny.

 

[james49]

"NuBee here. It has been suggested to me to run Pennzoil Synchromesh in the transmission & rear diff. of my 96 miata. Owner,s manual says API GL 4-5 for trans & GL-5 for rear. Found out that the Pennz has no API GL rating. Is someone trying to pull my Yittle Yegg or what?"

Not all manual transmissions require a GL4 only rated oil. Yours may be better with Amsoil Sever Gear 75w90 or Royal Purples 75w90. Both are both GL4 and GL5 rated.