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2003 S-10 Blazer - transmission?

My 2003 S-10 Blazer has 175,000 miles on it. I got it in 2005 with 38,000 miles on it. As far as I know, at least while I’ve owned it, the transmission has never been serviced, fluid change, flush or the like. Lately, it has started to be sluggish getting up to speed or going up hills. Engine rpm goes up, but vehicle speed only goes up very slowly. I have checked and added a pint of transmission fluid each week for the last month or so. Probably time to get service - but: just a fluid change or flush ? And I’ve heard that older transmissions that were never flushed can be damaged by flushing, and end up needing a rebuild - $$$$ !

Comments, anyone ?

I have heard that story too, it is not that they are damaged but revealing a weakness, imho. You are having problems and problems with cars tend to get worse as time goes on, not better. I would try a flush and filter on the tranny hope for the best, and not be surprised if a rebuild is in the near future. It would also be a good time for a coolant flush and refill with peak global or similar! As far as sluggish it is time for new plugs if that has never been done, how about a new gas and air filter, do you change oil and do any regular maintenance on it?

Over the holidays, new plugs, air filter, and fuel filter were put in. And I have the oil, filter and lube done with full synthetic evry 10,000 miles. Thanks for the advice though. Had a recent post (moody heat) where I discovered I was low in coolant. I have added a qt. to half gal of that each week also. Need to keep expenses down, so I’m adding coolant but will look at the transmission flush (and pray !) Thanks.

The coolant loss could be a bad head gasket accounting for coolant use and bad mileage and loss of power, unless you see a coolant leak somewhere. I think it might be trade in time.

“I have checked and added a pint of transmission fluid each week for the last month or so.”

If your transmission is leaking a pint of fluid per week, it is in need of a lot more than just a fluid change. I suggest that you take the vehicle to an independent transmission shop (NOT AAMCO, Lee Myles, Cottman, or any other chain operation) for an evaluation.

I read the last reply with coolant leak, and did not catch the transmission leak in the op, good catch, time to have a serious evaluation?

Why is it that you kept up with the oil changes religiously every 10k but never serviced the transmission? It went at least 140k (That we know of) without being serviced. This trans should have been going on its 7th service right now, in fact, doing a trans service on your own will cost less than one of your 10k oil changes using synthetic oil. Now that its acting up, you want to service it. As ok4450 says, you’re closing the barn door after the horses got out. If the fluid level is good and its still slipping, your 3-4 clutches are shot and you are looking at a rebuild. Remember, in the future, automatics need to be serviced every 25-30k miles regardless of what your owners manual says. There is no such thing as lifetime fluid. Properly serviced, you probably could have got another 50-75k out of this trans.


It is a cart and a horse issue. You are suppose to change the fluid to protect the transmission, not to fix it.

A lot of people do try their first transmission fluid change after they start having a problem. Well the damage has been done and then the transmission crashes. So rather than accepting that they make a mistake by not servicing the transmission when they should have, they blame it on having the transmission serviced.