Background:
I have a 1990 Saab 900 base model (2.0L n/a 4cyl @ 128hp), with 166k miles on the original 5sp tranny (& engine). I bought it about 5 yrs ago, & it had 113k miles on it at that time. The PO had it serviced at the same place I take it to, & the tranny lube had always been 75wt dino gear oil (sometimes with BG MGC added).
About 40k miles ago I started having a 5th gear problem. When I'd run the car for 20min-30min on the freeway, & everything heated up real good, I couldn't get it out of 5th gear! It took a few really hard yanks on the shifter to get it to let go, & then it wouldn't go back in until everything had cooled down (e.g., parked for a couple of hours). At that time, my mechanic resolved the problem by draining the 75wt gear oil, refilling with tranny cleaner & motor oil, running it for 1/2 hr, draining it, refilling with only motor oil, running it for another 1/2 hr, draining it, & refilling with BG SyncroShift II syn gear oil. After all of this, the car shifted better than when I bought 1yr earlier. About 10k miles later I knocked out the shift shaft seal & had to add motor oil for a day to keep the level up. My mechanic then drained out the mix, replaced the seal, & refilled again with BG SS2. Shifting was still great.
Current:
Now it's about 30k miles later, & I still have that second fill of BG in the case. And the 5th gear problem returned. So I decided to tackle it myself this time, either saving a few hundred dollars in mechanic time, or potentially costing several thousand dollars when I severely hose up my tranny.
I added 3oz of Auto-Rx to the 3qts of syn gear oil. The instructions for dino oil are to leave it in for 1,000 miles, but for syn oil Frank said it's 1,500 miles. Since I'm having the stuck-in-5th problem again, I decided to run it for 2,000 miles.
I noticed no change for the first 200 miles or so. Then, everything seemed to get just a little bit smoother & the sticking problem vanished. Things continued to improve very slightly until about 500 miles into it, & then it stabilized for the remainder of the application.
Since my mechanic had run the solvent flush followed by the motor oil flush, & I had unexpectly had a short run of syn lube followed by a normal run of syn lube, I really wasn't expecting to see much contamination in the oil. But that oil looked pretty cloudy as it drained out of the case. The Auto-Rx seemed to do what it claimed, & I was glad to get that junk out of there. Additionally, there was a hefty amount of metal filings on the magnetic plug.
Then I decided to do what everyone says not to on these older Saabs: switch from gear oil back to the factory-recommended motor oil. The manual lists 10W-30 or 10W-40, & I decided to use Delvac 1300 Super 15w40. Its specs show that it cold-flows as well as the 10W-30 version, so I used 2 qts of that. Since we're heading into winter, I also mixed in 1 qt of Mobil 1 10W-30 to "enhance" the cold temp characteristics & give a bit more moly.
So far, everything's working great, but when the temps drop below freezing my cold shifts are notchy-er than they used to be. Once the tranny absorbs all the heat from the engine, shifting's fantastic, but I'll probably just use Rotella Syn 5W-40 next time.
Due to the amount of crud the Auto-Rx pulled out, I'm planning on changing the oil again this coming summer, & then maybe once a year after that. This will be a big change from what the car's seen for the past 15 yrs, so I hope things progress positively. I'll let everyone know what I find in there at the next drain interval, or if everything blows up before then.
I've also given the engine a new oil filter & 10oz of Auto-Rx added to the 6,500-mile-old Mobil 1 15W-50, to start a triple-length-application to clean things out in there. I'll swap in a new oil filter every 1,500 miles for the next 4,500 miles, & I'll open up each filter to see what's getting caught. I'll post on how that goes ...
I have a 1990 Saab 900 base model (2.0L n/a 4cyl @ 128hp), with 166k miles on the original 5sp tranny (& engine). I bought it about 5 yrs ago, & it had 113k miles on it at that time. The PO had it serviced at the same place I take it to, & the tranny lube had always been 75wt dino gear oil (sometimes with BG MGC added).
About 40k miles ago I started having a 5th gear problem. When I'd run the car for 20min-30min on the freeway, & everything heated up real good, I couldn't get it out of 5th gear! It took a few really hard yanks on the shifter to get it to let go, & then it wouldn't go back in until everything had cooled down (e.g., parked for a couple of hours). At that time, my mechanic resolved the problem by draining the 75wt gear oil, refilling with tranny cleaner & motor oil, running it for 1/2 hr, draining it, refilling with only motor oil, running it for another 1/2 hr, draining it, & refilling with BG SyncroShift II syn gear oil. After all of this, the car shifted better than when I bought 1yr earlier. About 10k miles later I knocked out the shift shaft seal & had to add motor oil for a day to keep the level up. My mechanic then drained out the mix, replaced the seal, & refilled again with BG SS2. Shifting was still great.
Current:
Now it's about 30k miles later, & I still have that second fill of BG in the case. And the 5th gear problem returned. So I decided to tackle it myself this time, either saving a few hundred dollars in mechanic time, or potentially costing several thousand dollars when I severely hose up my tranny.
I added 3oz of Auto-Rx to the 3qts of syn gear oil. The instructions for dino oil are to leave it in for 1,000 miles, but for syn oil Frank said it's 1,500 miles. Since I'm having the stuck-in-5th problem again, I decided to run it for 2,000 miles.
I noticed no change for the first 200 miles or so. Then, everything seemed to get just a little bit smoother & the sticking problem vanished. Things continued to improve very slightly until about 500 miles into it, & then it stabilized for the remainder of the application.
Since my mechanic had run the solvent flush followed by the motor oil flush, & I had unexpectly had a short run of syn lube followed by a normal run of syn lube, I really wasn't expecting to see much contamination in the oil. But that oil looked pretty cloudy as it drained out of the case. The Auto-Rx seemed to do what it claimed, & I was glad to get that junk out of there. Additionally, there was a hefty amount of metal filings on the magnetic plug.
Then I decided to do what everyone says not to on these older Saabs: switch from gear oil back to the factory-recommended motor oil. The manual lists 10W-30 or 10W-40, & I decided to use Delvac 1300 Super 15w40. Its specs show that it cold-flows as well as the 10W-30 version, so I used 2 qts of that. Since we're heading into winter, I also mixed in 1 qt of Mobil 1 10W-30 to "enhance" the cold temp characteristics & give a bit more moly.
So far, everything's working great, but when the temps drop below freezing my cold shifts are notchy-er than they used to be. Once the tranny absorbs all the heat from the engine, shifting's fantastic, but I'll probably just use Rotella Syn 5W-40 next time.
Due to the amount of crud the Auto-Rx pulled out, I'm planning on changing the oil again this coming summer, & then maybe once a year after that. This will be a big change from what the car's seen for the past 15 yrs, so I hope things progress positively. I'll let everyone know what I find in there at the next drain interval, or if everything blows up before then.
I've also given the engine a new oil filter & 10oz of Auto-Rx added to the 6,500-mile-old Mobil 1 15W-50, to start a triple-length-application to clean things out in there. I'll swap in a new oil filter every 1,500 miles for the next 4,500 miles, & I'll open up each filter to see what's getting caught. I'll post on how that goes ...
