Add Trans Cooler and/or External Filter?

I just bought a used '00 Oldmobile Sihouette (same basic van as Venture & Montana). I want to drive it until the doors fall off (that’s what I do).

Minivan transmissions are known for being terrible. This one’s original failed at about 55K - the one in there now was a new GM install & has about 50K (van has 103K) on it. It shows absolutely no signs of trouble or abuse.

I plan to drop pan/filter now and every 30K.

I am also thinking of adding an aftermarket cooler. Is this a good idea? Does the brand or style matter? Is it a reasonable DIY job or best left to a shop? (I do all sorts of regular maintenance stuff - e.g. oil, trans pans, brakes).

I also stumbled across an add-on inline external filter. Looks to just plug into the cooler lines for extra filtration - apparently magnetic. I’m sure that’s an easy install, but is this kind of thing a good idea? Maybe change it every 10K and the internal every 30K?


An aftermarket transmission fluid cooler might add life to the transmission, especially if you plan to tow with it or haul heavy loads. The aftermarket filter is probably less legitimate.

I recommend the type of transmission fluid cooler that has its own radiator that usually attaches to the front of the stock radiator and I recommend professional installation.

Regarding frequency of the fluid change, rather than adjust it, keep a close eye on the fluid to check both the level and, more importantly, the condition of the fluid. You might also consider looking into a fluid upgrade. Try to find a tansmission fluid that is approved, but of higher quality than what is normally used.

I would be careful of the filter. If it is poorly designed it could restrict flow and cause damage. What kind of cooler is on the van now?

The external cooler is a great idea and can really help the lifespan of the transmission.
They’re cheap, easy to install, and if you don’t butcher up the original cooler line ends (a couple of female barbs can be used rather than cut the ends off), the cooler can be removed if you go to sell or trade the vehicle later. It can then be used on your next vehicle.
Think of the gift that keeps on giving.

Any of them will work jsut fine. I might pass on the filter though. The filter in the pan will catch anything of importance and besides, much of what you may see in the pan is non-magnetic anyway. Most transmission drain plugs are magnetic and that should take care of any tiny bits that are ferrous.

They Might be easy to install would be my caviot, but yes it is a good addition.

You are correct in identifying the transmission as a point of concern,another weakness is in the intake manifold sealing,keep your eye on it.

Ahh…nicely enough the intake manifold gaskets were replaced about 10K ago. I had specifically looked into that as I had heard of GMs intake problems. (I once had someone tell me - only halfway joking - that 100K was a great time to buy a vehicle b/c the prior owner had already needed to get all of the kinks out).

I haven’t taken a close enough look to see how the trans is currently cooled, but it sounds like the idea is that it can’t hurt and is very likely to help. I am still wondering about the install. Whitey makes me want to take it in & cough up the $$ - ok has me popping one on the next time my hands are dirty.

Sounds like no confidence in the filter. I have just always wished I could just as easily change my tranny fluid/filter as the engine oil/filter - so an external filter just looked nifty. As I was googling about re: coolers, here is what got me thinking about that:
This page is all about racing mods, so some of the stuff will be nuts, but I was struck by this general idea, and then saw some simpler & less elaborate things

Thanks for the input

I know it’s just a figure of speech, but these sometimes do have problems with the sliding doors falling off. So maybe you’ll be able to drive it PAST when the doors fall off!

I agree with the others that an extra cooler is a good idea, but the extra filter is totally unnecessary, since there’s not really a source for a lot of foreign material in your transmission and the stock filter picks it up fine.

On a slightly different subject - does anyone know what is up with the teeny little oil filter on these vans? Its a 3.4L 6 and the oil filter looks about the size of the one on my lawn mower. I find it disturbing.

The lawnmower filter is really too big as far as filtering goes. It is that size because of the 30 weight oil it has to filter. We don’t want to strain a lawnmower oil pump. We all wish for the standard Fram PH8A size filter, but don’t need one that big. We aren’t filtering out rocks or dirt after all. Water is the worst thing to get into oil and the filter is useless against that. It does what it is designed to do.

Bigger isn’t necessarily better when it comes to oil filters. In fact, some smaller filters are rated higher than some larger filters.

If it makes you feel better, check out other brands of oil filters. I personally like Purolator.