I'm somewhat confused about tranny gear oil weight...

[H.G.P.]

My Haynes says, "SAE 90EP to specification MIL-L-2105 or 2105B. For limited slip differential versions use oil to specification M2CB (eg: Shell S 1747A) only" page 94,

1. What defines a heavy weight gear oil? (80? 90?.... is the higher the number the "heavier the weight?)

2. what do all the letters and numbers represent?

3. How does the above compare with the Swepco types?


Thank you. (I have a 901 manual 5 speed)

[Early_S_Man]

HGP,

'Heavy' gear oil would be SAE 140 or SAE 85W-140. Normal would be the SAE 90, SAE 75W-90, or SAE 80W-90.

Swepco 201 is a 'normal' weight gear oil.

If your climate reaches 100°F+ temps in the summer, then my recommendation would be to use Swepco 212, a multi-weight SAE 80W-140 gear oil with moly.

http://www.pelicanparts.com/catalog/shopcart/CARE/POR_CARE_swepco_pg4.htm

[DonDavis]

On Warren's recommendation, I am going with Swepco 212.

[H.G.P.]

I've not located Swepco around here yet, I do have 85W-140 in there now.

What is the signifigance of the usage of two simultaneous numbers here both 85 and 140?

[sammyg2]

That just means it is a multi-grade viscocity rating.
Additives are blended in to the oil so that when cold it flows and performs like an 85w oil (in theory, anyway) and when hot has viscosity characteristics similar to 140 weight.
It is not the same, but they try. The only advantage in using 85w140 is if you are in a place where the ambient temperature changes a lot.
If you drive when it's 30 degreees F and then it gets to 100 F, you prolly need the multi-viscosity blend. If you are in southern California and it swings from 50 to 85 degrees when you drive, you don't need the wide blend.
I'm a firm believer that a straight weight gear oil works better than a multi-vis if it is consistant with the operating conditions.

[Early_S_Man]

Sam,

Strictly speaking, the two-number-with-W-suffix-on-the-first has nothing to do with multi-viscosity rating ... it means two different test temperatures, 0°F and 212°F, with the 'W' designating the winter test at the lower temperature. Generally, these days, the 'W' designation is left off on 'Straight' rating oils. BTW, gear oils were given a higher 'number' value range back in the 1940s to keep people from confusing gear oil and motor oil ... a little-known fact I picked up from a John Deere guide to oils! SAE 75W gear oil is approx. the same viscosity as 10W motor oil, and SAE 90 gear oil is approx. the same as SAE 40 motor oil.

BTW, my '73 owner's manual had SAE 20W-20 motor oil listed as a recommended grade in Alpine conditions where temps never get above 40°F! I guess the 20W-50 Valvoline has that covered pretty well ...

I had great luck with SAE 90 Valvoline gear oil in winter months and SAE 140 Valvoline gear oil in spring/summer months back in the early years ... when gear oil got changed at every engine oil change, per the owner's manual! I first used straight SAE 90 Swepco 201, too ... the gold variety, with a bit longer change interval! When I first mentioned it on this board a few years ago, I might as well have been talking about oil drilled on Mars, as nobody knew about anything but BLUE Swepco 201 ... though the straight SAE 90 gold is still available!

Rather than ask Wayne to get the gold Swepco ... I opted for the 212, and he came through like a champ!

[Flying Toaster]

Does anyone have pictures or more details on where the drain & fill points are for a 915? (newbie question)

Also, 75-90 is acceptable for a high mileage New England climate tranny?

TIA - John

[Flying Toaster]

Nevermind. Just found a picture on page 11 of the Haynes manual. Is there a trick to filling the fluid at that angle?

[ubiquity0]

You need to teleport yourself to the Haynes Manual parallel universe, & will find that the rest of your car temporarily magically disappears, giving easy access to the fill plug

[ubiquity0]

I've had limited success with cheap fluid pumps- usually it gets messy. Next time I'm going to try the gravity method- a few feet of plastic tubing, a funnel & a patient helper.

[Early_S_Man]

I am convinced that changing gear oil can't be done without some spillage, hence expendable clothing, or 'work' clothes that get washed alone and are expected to have petroleum on them from time to time are the best choice.

As to pumps ... I have tried the not-so-cheap screw-top variety that fasten to oil bottles ... and I say forget them! The best pumps and chance for least spillage are the metal 'syringe' style that hold a pint or so, and the plunger can be quickly reversed to suck as much as possible back into the cylinder when overflow of the filler hole occurs. Have spray degreaser and paper towels at hand to clean up the transaxle ... after you install and torque the filler plug!!!

[ChrisBennet]

I just use a home made "pump" to fill transaxles. A get a few dribbles from the fill hole but no mess to speak of. My pump is just a juice jug with 2 holes in the lid; one for the fill hose and another hole that I apply compressed air to.
-Chris

[HarryD]

Originally posted by Flying Toaster
Nevermind. Just found a picture on page 11 of the Haynes manual. Is there a trick to filling the fluid at that angle?

Not really, you can go the "yankee ingenuity" method and use a funnel and 3 ft of 3/4" tubing. You attach the tubing to the funnel, snake the other end of the tube through your wheel well and stick it into the fill hole, hold the funnel above the wheel wheel and pour the oil into the funnel. When you see oil dribbling out of the fill hole (about 3 quarts later), you are done.

Here's a pretty clever way:

[911pcars]

Harbor Freight (HF) currently has the pump-suck type on sale in their catalog. Regularly ~$11; it's now ~$5. It works well and spillage is at a minimum, but I'd recommend the latex gloves, paper towels and carb spray cleaner for cleanup. ...

....and the reminder to first remove the filler plug before draining the gearbox. You don't want to be stuck with an empty tranny in case the filler plug doesn't want to come out.

Sherwood

[Wayne 962]

Originally posted by Early_S_Man
Rather than ask Wayne to get the gold Swepco ... I opted for the 212, and he came through like a champ!

Right - based on Warren's recommendations, we started carrying this weight...

-Wayne

[sammyg2]

http://www.vtr.org/maintain/oil-overview.html