I looked through all the old threads on transmission fluid but I couldn't find anything on mixing fluids.
I currently have Swepco in the transmission. Is it okay to top it off with a GL-5 non-detergent 90w oil? If not, would another brand detergent GL-5 90w gear oil be okay?
I'm trying to avoid Swepco because it is expensive and hard to find locally in the North san Deigo county area.
Full Version: Transmission Fluid Mixing Question
I wouldn't. Drain it and refill with plain old 80/90 GL5. DO NOT use anything with friction modifiers! DO NOT use anything that says anything other than GL5! And, for your own protection, loosen the fill plug BEFORE you drain the transmission.
The Cap'n
The Cap'n
....And , never good practice to mix fluid's(tranny or engine) 
Be careful calling transmission gear oil "fluid". Different stuff.
Iv always been told swepco is the only oil to run in a porsche box. Any german shop should had it on hand.
I know its not the right thing to do but i have a good mix or cocktail in the 091 vanagon box. The redline was to thin and was getting hot in the summer months and the castrol was to thick in the winter ski trips So a 3 part Castrol 1 part redline seems to be working perfect. But i am running X2 horse power and trok with 17 inch tires.
The biggy is the GL-5. I had the oil changed in the toyota at the dealer on a no charge oil change. They did the diffs and tranny and transfer as a thank you! But they put the same GL-4 in everything!! I almost had to double clutch it to get it home. wrong oil Total screwed with the syncros.
jcl
I know its not the right thing to do but i have a good mix or cocktail in the 091 vanagon box. The redline was to thin and was getting hot in the summer months and the castrol was to thick in the winter ski trips So a 3 part Castrol 1 part redline seems to be working perfect. But i am running X2 horse power and trok with 17 inch tires.
The biggy is the GL-5. I had the oil changed in the toyota at the dealer on a no charge oil change. They did the diffs and tranny and transfer as a thank you! But they put the same GL-4 in everything!! I almost had to double clutch it to get it home. wrong oil Total screwed with the syncros.
jcl
QUOTE(a914622 @ Feb 28 2013, 12:23 AM) 
Iv always been told swepco is the only oil to run in a porsche box. Any german shop should had it on hand.
I know its not the right thing to do but i have a good mix or cocktail in the 091 vanagon box. The redline was to thin and was getting hot in the summer months and the castrol was to thick in the winter ski trips So a 3 part Castrol 1 part redline seems to be working perfect. But i am running X2 horse power and trok with 17 inch tires.
The biggy is the GL-5. I had the oil changed in the toyota at the dealer on a no charge oil change. They did the diffs and tranny and transfer as a thank you! But they put the same GL-4 in everything!! I almost had to double clutch it to get it home. wrong oil Total screwed with the syncros.
jcl
Swepco is far from the only oil to use. But it is your money so feel free to piss it away.
Dont mix.
QUOTE(a914622 @ Feb 27 2013, 09:23 PM)
Iv always been told swepco is the only oil to run in a porsche box. Any german shop should had it on hand.
I know its not the right thing to do but i have a good mix or cocktail in the 091 vanagon box. The redline was to thin and was getting hot in the summer months and the castrol was to thick in the winter ski trips So a 3 part Castrol 1 part redline seems to be working perfect. But i am running X2 horse power and trok with 17 inch tires.
The biggy is the GL-5. I had the oil changed in the toyota at the dealer on a no charge oil change. They did the diffs and tranny and transfer as a thank you! But they put the same GL-4 in everything!! I almost had to double clutch it to get it home. wrong oil Total screwed with the syncros.
jcl
People who tell you Swepco is the only gear oil to use are trying to justify the money they spent on it, or they're selling it and enjoying the markup. Porsche ran GL5 for decades before Swepco and other synthetics ever came to market, and it worked just fine for all those years. Just 'cause it's newer and/or costs more doesn't make it better, just different. In fact, some newer stuff is actually a DOWNGRADE.
The Cap'n
I was always told that Swepco was too slippery, and didn't adequately slow down the gears enough to mesh smoothly on a quick shift. The Porsche Synchromesh system uses friction to help slow down or speed up the gear being selected. Anything too slippery seems like it negatively impact that. I've only ever run Dino 80/90 GL5 and I've never had an issue.
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