G50 Tranny Fluid Flush Advice

spedrcr · 07:20 PM

I drained the 2 year/5,000 miles fresh Swepco 212 80W-140 gear oil from my 144Kmi G50 tranny. It's like jelly it's so thick. Before I fill with Mobil Delvac, I want to flush out the jelly. I purchased Valvoline 80W-90 dino gear oil with API GL-5 rating. It does however say it is for NON-syncromesh manual transmissions.

My thought was to fill with Valvoline and run the car through the gears while on jack stands, warm the oil in 3rd gear at 3Krpm, maybe 30 mins total and then drain it. Any concern with the NON-syncromesh rating? No real shock on the gears as I'll double clutch and rev match. Any BTDT's on gear oil flush?

Thanks in advance.

DRACO A5OG · DRACO A5OG's Garage

Well to quote Master Zimmerman,

When I asked about flushing the gear box, he recommended using the same product that I want to stick with. He recommended flushing twice maybe a third time to be sure.

Yes, I know it will get expensive but think about the cost of a rebuild.

Wow 80W140, that is pretty thick.

spedrcr · 02-23-2017, 07:21 PM

That does make good sense and it certainly could get expensive if using the Delvac as the flushing fluid. Something to consider though.

Canada Kev · 02-23-2017, 07:47 PM

Quote:

Originally Posted by DRACO A5OG

Well to quote Master Zimmerman,

When I asked about flushing the gear box, he recommended using the same product that I want to stick with. He recommended flushing twice maybe a third time to be sure.

Yes, I know it will get expensive but think about the cost of a rebuild.

Wow 80W140, that is pretty thick.

And it almost justifies buying that 5 gallon pail of the oil that seems much easier to find than smaller, more manageable container sizes. Well, at least up here in the Great White North its difficult to find the 1 or 4 quart sizes...

s5uewf · s5uewf's Garage

I would just put in what you intend to run going forward, drive it a short interval (like a few hundred miles - it won't hurt anything if the lubes are compatible) to really mix up all the lube and then drain and refill again. Just rinsing it through may not really pull all the old lube off the internals. Just my two cents

spedrcr · 02-24-2017, 04:56 AM

Another good point. A couple hundred miles would certainly be more thorough of a "rinse".

Trakrat · 02-24-2017, 07:29 AM

Just curious... Do you need to bang through all the gears to make sure it's properly lubed and moved around?
And then do you drain the fluids immediately after a driving? (I'm not sure how warm the transmission fluids get)
And finally... does the transmission trap some of the oil? Do you need to shift through the gears as its draining to make sure any pressure built up is released?

Tippy · 02-24-2017, 07:43 AM

Quote:

Originally Posted by s5uewf

i would just put in what you intend to run going forward, drive it a short interval (like a few hundred miles - it won't hurt anything if the lubes are compatible) to really mix up all the lube and then drain and refill again. Just rinsing it through may not really pull all the old lube off the internals. Just my two cents

+2

s5uewf · s5uewf's Garage

If you have an LSD in the trans also check in case you need to add any additive for the LSD. Not sure about G50, but in my 930 I needed to add some LSD specific lube along with the gear oil. Just something to be aware of. G50 is such a nice shifting trans...

spedrcr · 02-24-2017, 07:49 AM

In response to Trakrat-The oil certainly gets warmer with a drive. And I would think it's better to get through all the gears than not. Consensus on changing gear oil is do it when its "hot" so it flows easier and more old comes out. Same applies for new oil going in. Warm up in buckets of hot water. Easier to pump/flow.

I have found my "flush" oil with Chevron Delo Syn Gear XDM 75W-90 with a GL-5 rating. $25 bucks for 4 quarts and fewer worries than the non-syncromesh rated Valvoline. I'm confident my notchy shifting will improve with the Chevron to start as Swepco 212 is far too heavy of an oil at 80W-140 for my street application. Hope to get Mobil Delvac in at the next engine oil change, approx 1500 miles from now.

No LSD in my G50. Bummer.

Matt Monson · 02-24-2017, 08:18 AM

You will want to get out and drive the car. The moly from that 212 will be everywhere and just running through the gears on a lift won't do much. If it were my car I would drive it for 1000 miles or so and then change it out.

Don't worry about the synchro mesh thing. Most GL5 oils were developed for non-synchro boxes.

spedrcr · 02-25-2017, 06:54 AM

Filled the transaxle with Delo synthetic 75W-90 yesterday. Almost 3.5 quarts until it started running out the fill hole. I'll run it for 1500 miles and change it out to the Delvac when I change the engine oil. Looking forward to running it through the gears soon. I'll report my findings. Based on how thick the Swepco 212 is, I'm confident the Delo will give me smoother shifting.

spyerx · 02-26-2017, 06:10 AM

My g50 had swepco in it. Delvac put in a year ago is much smoother shifting but lsd makes some noise (expected). When cold it is a little notchy. All tood when warmed up

On my 997rs I ran delvac for a few years and recently switched to motul 75w140 competition. Shifts better cold and hot.

I'm going to pull the delvac out and go to motul 75w90 with lsd friction modifier in the 89. Full synthetic.

Delvac is good stuff. So is motul.