1979-1993 & 94 Conv [Subscribe to Daily Digest] |
Members do not see ads below this line. - Help Keep This Site Online - Signup
Background:
I have a 1990 base model, with 165k 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.
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 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 3 yrs 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 with BG SS2. Shifting was still great.
Now it's about 25k-30k miles later, & I still have that second fill of BG in the case. And the 5th gear problem returns. So I decide 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 tranny, following the tranny-specific directions of 1oz per qt of oil (this is a different ratio from the engine application). The instructions for dino oil are to leave it in for 1,000 miles, but for syn oil it's 1,500 miles. Since I'm having the stuck-in-5th problem, 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. This past Sunday, I drained everything out.
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 opaque 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.
I decided to do what everyone says not to: switch from gear oil to motor oil. Only, I really wanted to use a diesel-style oil for its extra additives & durability. The specs on Delvac 1300 Super 15W-40 show that it cold-flows as well as the 10W-30 version (equal to a low-75wt gear oil), & the heavier hot viscosity (equal to a low-90wt gear oil) should increase bearing protection. I used 2 qts of that. Since we're heading into winter, I also decided I wanted to improve the cold-flow characteristics even more, so for the 3rd qt I used Mobil 1 10W-30. Since this is probably Mobil's most shear-resistant oil, I think it's a good match for the application. Also, its PAO basestocks & touch more moly make me feel better about changing from gear oil to motor oil.
So far, everything's working great. But I only have 175 miles on the new oil. Due to the amount of crud the Auto-Rx pulled out, I'm planning on changing the oil again in about 6 mos or so, & then 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. (yikes!)
This weekend, the engine gets a new oil filter & 10oz of Auto-Rx (2oz per qt of oil, plus 2oz "for the filter", added to the 6,500-mile-old Mobil 1 15W-50), & I 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 ...
Let me know what you think, & I'm happy to answer any questions. (Hey, what's a guy with MAS supposed to do?) :-)
posted by 64.207.44...
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
