My S70 developed a slight transmission leak, which turned into a serious one after about a week. Not wanting to spend more money than the car was worth on repairs, I set out to try and find a cheap solution. You may benefit from what I did to stop it, or you may take serious issue with it, but either way, it worked!


At the peak of the problem it was using about a quart of fluid every three days. I never determined exactly which seal was leaking, because the fluid seemed to be coming from more than one.


I read about Blue Devil transmission seal, so I used about 8 ounces of a 16 ounce bottle. After about 24 hours, the leak had decreased by about half. By a few days later the leak had begun to increase again, so I added the other 8 ounces. I was also adding transmission fluid according to the owners manual which called for Dexron/Mercon. Again, the leak decreased slightly, but was still using about a quart of fluid every 6 days.


It was at this point that the transmission started going into limp-mode on a regular basis. It would start off in 2nd gear and shift very hard into reverse. Also, if you accelerated from a start, but then hit the brakes, the transmission wouldn't downshift and the engine would stall.


I then spoke to a Volvo technician and he told me that the owners manual is wrong and to never use Dexron/Mercon. He said the limp-mode was caused by a sudden viscosity change in the fluid. He recommended draining the transmission fluid and re-filling with genuine Volvo fluid, (which was quoted at $33 per quart), which would have cost me $231 in fluid alone.


I then read about Toyota T-IV fluid and how it is the same formula as genuine Volvo fluid, but only $8 a quart. After adding the first quart of Toyota fluid, the leak began to subside. After three quarts, the leak stopped altogether and it hasn't leaked a drop now in over a month.


I think that the Blue Devil slowly re-hydrated the seal and, had I used the correct fluid to re-fill the transmission, the leak would have then stopped over time anyway. But I can say that since I added the Toyota fluid, the S70 has shifted better than it ever has before.

 

Different Volvo models use different transmission fluids. Some use Dextron III, some use JWS 3309. Best to research exactly what is required for your car. Incidentally Toyota T-IV is spec'd for JWS 3309, so that works for models requiring that standard.