vincentmoy Posted January 5, 2011 Share Posted January 5, 2011 I have a 2003 Forester with about 149k miles on it. It's a 5 spd and everything is running smoothly. The other day I got some gear oil (Valvoline Durablend for trans and syncpower for rear diff.) to get ready to change the fluid in my trans and rear diff. But I talked to a co-worker, who was an auto mech. said I should NOT change them and it's a waste of money. I am just wondering what is your take on that. Thanks! Quote Link to comment Share on other sites More sharing options...
Suzam Posted January 6, 2011 Share Posted January 6, 2011 Is your co-worker (the auto mechanic) employed as one currently? How much money is waste? You already bought it. For piece of mind and preventative maintenance, I change all of the fluids on a regular basis. I change out rear diff and front transfer oils between 80 & 100K in my auto Subies. If nothing else a cleaner, correct viscosity oil has less drag on the drive train than oil with dirt and metal suspended in it and lubricates better. Maybe it is a waste but I'm happier after it's done. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted January 6, 2011 Share Posted January 6, 2011 It's not going to hurt anything - might even prolong the life of the bearings a bit. The 5MT's tend to last about 250k give or take - doesn't really matter if you change the fluid or not. Being as there is no contaminates other than what the transmission makes on it's own from gear wear (wihch gear oil does a great job of suspending) it's not really going to matter. I know of 5MT that have died at 200k with fairly regular gear oil changes and I know other's that have lasted (and are still going) at 270k without ever being changed. Luck of the draw mostly. So yeah - it's probably a waste of money but if it makes you feel better go right ahead. You might be very alarmed by the amount of metal that comes out of a manual tranny..... so that's one reason to not touch it. If you don't see it you might not worry about it so much. If you are not used to draining MT's and seeing that much ground up steel I mean..... GD Quote Link to comment Share on other sites More sharing options...
edrach Posted January 6, 2011 Share Posted January 6, 2011 I can understand the bearings lasting 250K miles in a 5MT transmission, but I've found the synchro (especially 2nd) starts to crunch around 150K. I don't think gearoil will change that symptom much, but I've had good success with Redline NS gearoil in extending the life of the synchros. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted January 6, 2011 Share Posted January 6, 2011 People forget that these have a differential stuffed underneath the gear case, and diffs are much more susceptible to damage from old gear oil. But differential failure in the MT is much less common than the main shaft roller bearing failure, and the guaranteed worn out synchros. It won't hurt, but it probably won't help much either. You get 100k more miles out of it and by then the rest of the car will be worn out just as much and ready for the scrap yard, or to become someones weekend off-road basher. Quote Link to comment Share on other sites More sharing options...
edrach Posted January 6, 2011 Share Posted January 6, 2011 People forget that these have a differential stuffed underneath the gear case, and diffs are much more susceptible to damage from old gear oil. But differential failure in the MT is much less common than the main shaft roller bearing failure, and the guaranteed worn out synchros. It won't hurt, but it probably won't help much either. You get 100k more miles out of it and by then the rest of the car will be worn out just as much and ready for the scrap yard, or to become someones weekend off-road basher.I'll agree with the first half of the comments, but disagree with the 2nd half that indicates the car would be ready for the scrap yard with high mileage. I have a '97 Impreza which is my daily driver as well as a rallycross warrior for the last 6 years I've had it. It's on a rebuilt engine (previous owner didn't change the oil as often as he should have) and a replacement transmission (rallycross IS hard on the transmission), but the car turned 200K miles yesterday and should still be good for another 100K with just routine service. Fortunately, I no longer live in the rust belt east coast. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted January 6, 2011 Share Posted January 6, 2011 Rust, maybe. He lives in AK, don't know if they salt the roads like it's going out of style the way they do here. But suspension parts will be well worn, wheel bearings, U joints, engine might be worn out, transmission, anything that moves basically, will almost certainly be ready for overhaul or replacement by 250k miles. So you either dump a ton of money into it on parts, sell it to someone else who wants to, or scrap it. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.