G50 Synthetic Tranny Oil Change Completed (pics)

mthomas58 · 09:41 AM

Completed gear oil change today with Valvoline 75W-90 Synthetic in hopes that cold shift performance will improve. Thought I would share some observations and pics. This was a very easy DIY project. Update 1-2-07: 36 degrees this AM in Atlanta - no cold shift problem!

With the rear end on jack stands and rear driver side wheel removed, I was surprised to find that the filler plug was not located higher on the tranny housing. In fact, when I removed the filler plug, approx 1/2 quart of oil came out. Immediately, I realized that the left side of the car would need to be jacked as high as possible on refill.

Working area under the car is very tight and leverage is difficult. I don't have a breaker bar or ratchet extensions for proper leverage, but a couple of taps on my ratchet handle with a rubber mallet worked well. After removing the filler plug (10MM hex) I then removed the magnetic drain plug and was happy to see that it was very clean

. I then lowered the rear of the car and raised the front to drain as much of the old oil. An additional 1/2 quart came out by raising the front end.

To refill, I ran a length of 5/8" clear tubing through the wheel well into the filler hole. After filling with the first quart which went slow due to the lack of airflow, I cut the quart bottle in half and used it as a funnel and things went faster. Refill took a total of 3 and 3/4 quarts.

My service records indicate that the gear oil was changed 30,000 miles ago and I now have 145k on the clock. I've got no idea what was used at the last change, however, the old oil smelled much like the new synthetic.

The car shifted smoothly on test drive, however, the true test will be the next cold morning. I'll report back with an update.

Filler plug location:

Filler on left, drain on right"

10MM Hex plugs - magnetic drain plug on right

Filler set up:

Elombard · 12-29-2006, 08:07 PM

I like the filler set up Mark, maybe we should come up with a tool name :-) T 1000.5??

eaipvc · 12-30-2006, 04:21 AM

Mark, Thanks for the post. I changed the gear oil in my 88 G50 this past summer. Used Mobil Synthetic gear lube 75W-90 (since I work for ExxonMobil the 10% discount on all products helps). The car has 75K and I believe it's the first time the gear oil was changed. Attached are pics of the magnetic plug. I found quite a bit of "gunk" on the plug. Can anyone tell me if this is a normal? I immediately noticed that gear whine was greatly reduced and possibly shifting was a bit easier. I took the car out yesterday (45F and sunny) and had some trouble selecting first gear. Car needed to be completely stopped and needed to engage second gear first then I could move to first. After a few miles the transmission warmed up and selecting first was not a problem. FYI, my A4 acts the same way when it gets cold.

livi · 12-30-2006, 04:46 AM

Good show!

I wish I had the brains to figure out that set up for filling when I did mine last summer. Crawling in and out from under the car with a 30 cm tube on a hand pump. Having a lot of that blue Swepco lube (915 box) all over me. Glad the change intervals are pretty extended.

88911coupe · 12-30-2006, 01:46 PM

It sounds like for eaipvc Mobil One did not really help. It's double the Castrol or Valvoline so are their valid benefits? I ask b/c I just bought 4 quarts of Mobil 1 75W90 and don't want to put it in and START having problems. I have Swepco in there now and it seems to work great but I could not find Swepco, not that I looked that hard.
Just wanting to make sure I'm not paying double for something that's not going to work as well.

kepperly · kepperly's Garage

I guess you guys haven't tried Redling 75-90 ns yet.

Keith Epperly
87 turbo look carrera cabriolet slant nose

hcoles · 12-31-2006, 11:41 AM

I've been using Redline 75W90 NS and sometimes I mix in one quart of Redline ShockProof gear oil...but probably adding the ShockProof oil is overkill.
-Henry
G50 - 89 3.2 ~10 track days a year

KTL · 01-01-2007, 11:35 PM

3-3/4 quarts is a lot of oil to add. You're probably overfilled since the factory documentation lists "approximately" 3 liters of 75W90 API GL5 gear oil as the capacity.

1 liter = 1.056 quarts and therefore 3L = 3.168 qt. You're a little over a 1/2 quart overfilled.

I would think any synthetic is going to do well for you since the factory fill was non synthetic. Everybody has their preference and the bigtime racers who prefer Mobil 1 say the best formula of that brand to use is Mobil 1 SHC 75W90. I tried it and noticed no major difference this year at track events (DE).

Zef · Zef's Garage

Nice set up...good tutorial for the Pelican mechanic wannabe...

Wavey · 01-02-2007, 05:53 AM

Quote:

Originally posted by KTL
3-3/4 quarts is a lot of oil to add. You're probably overfilled since the factory documentation lists "approximately" 3 liters of 75W90 API GL5 gear oil as the capacity. 1 liter = 1.056 quarts and therefore 3L = 3.168 qt. You're a little over a 1/2 quart overfilled.

I was thinking the same thing, Kevin. Not sure from reading the original post if the car was level when it was refilled or not, but it sounds like the left side was higher? Which, if it was filled to the bottom of the fill hole, would explain the overfilling. The car needs to be level left-right AND level front-rear. I found that by only lifting the rear, I was coming up 1/2 quart short on the refill. Raising the front to bring the car level allowed it to take the correct amount. The easy way to correct this would be to get the car raised and level, then remove the fill plug and let it drain to the bottom of the hole.

cnavarro · 01-02-2007, 06:34 AM

I'm running the mobilube SHC in my g50 now. In my previous experience in 901s and 915s, I found that the synchros and overall shifting was poor with the redline product - a quick change to SHC made shifting smoother and quieter.

carrera · 01-02-2007, 06:54 AM

mobil syn is working great for me in both the 915 and the g50.
Issues arise when there is considerable wear in either trany. otherwise this is great stuff.

Elombard · 01-02-2007, 08:10 AM

What is mobilube SHC? How do I identify it in the store? Is that a synthetic?

cnavarro · 01-02-2007, 08:13 AM

You can't purchase SHC in a store- it is different from the m1 formulation from your FLAPS. I get it from the big rig shop next door, as they buy it in 55 gal drums. Lufteknic is the only place I have found that has it in 1 gal containers.

cnavarro · 01-02-2007, 08:14 AM

And yes, it is a synthetic. Also sold under the delvac 1 brand in some places.

Elombard · 01-02-2007, 09:08 AM

Thanks Chales I will look for it at the APS that caters to big rigs in my area

mthomas58 · 01-02-2007, 09:24 AM

Cold Shift Update:

It was 34 degrees this AM and the car shifted like butter! No cold shift problems whatsoever.

cnavarro · 01-02-2007, 09:33 AM

Great to hear. I have been very happy with SHC in cold weather in both a 901 and g50 as well.

Wavey · 01-02-2007, 10:00 AM

Quote:

Originally posted by mthomas58
Cold Shift Update:

It was 34 degrees this AM and the car shifted like butter! No cold shift problems whatsoever.

Excellent! The Mobil 1 improved mine a lot too, but it's still slightly snug on the 1-2 shift when very cold.

You might consider draining the excess to get the level correct, if it is indeed overfilled. Too much oil + high temps = potential leaks.

KTL · 01-02-2007, 03:42 PM

Quote:

Originally posted by cnavarro
You can't purchase SHC in a store- it is different from the m1 formulation from your FLAPS. I get it from the big rig shop next door, as they buy it in 55 gal drums. Lufteknic is the only place I have found that has it in 1 gal containers.

Luftenknic is where I got my SHC. Great service and apparently good people too- they sent me a Christmas card.

http://www.lufteknic.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=Mobil75-90SHC&Category_Code=lubricants