I have a 1997 Diamante LS with 140K miles. I bought the car in Y2K with ~15K miles. It's been a generally reliable car but recently, I noticed a bit of transmission shudder in the 30-40 mph range. I recently read a TSB indicating the problem might go away if I use SPIII tranny fluid.

Not knowing what grade fluid might be in the tranny as I always paid someone else to change it, I decided to do it myself. So, I went down to Autozone in search of an SPIII fluid. They had a Lucas multi-vehicle fluid that claims to meet or exceed Mitsubishi Diamond SPIII

http://www.lucasoil.com/images/media...1983419411.pdf

I also bought a new filter.

I used brake cleaner to spray around the filter before removing it. I did notice it was a Mitsubishi filter which caused me to believe the shops that I paid to change the fluid never changed the filter. Anyway, When I removed the drain plug, there were a few small flakes of silver metal on it but not many.

I drained the tranny and replaced the fluid with the Lucas fluid. With the new fluid and filter, the condition improved but I can still get a little bit of shudder in the 30-40 mph range. The shudder generally occurs when I'm slowly accelerating. If I'm accelerating faster, the tranny shifts smooth.

When the shudder does occur, if i just let off the accelerator and then press it a bit harder, the tranny shifts smoothly.

My questions are:

1.) Should I drain the tranny again to get rid of all the old fluid?

2.) Is the Lucas tranny fluid ok or should I be strictly using the Mitsubishi SPIII from the dealer? If I should be using just the Mitsubishi fluid, why?

3.) Is there anything else I should be looking at?

Thanks.

FYI, to date I have:

Replaced alternator
Replaced all belts
Replaced valve cover gaskets
Replaced lower oil pan gasket
Replaced spark plugs
Replaced spark plug cables
Replaced distributor
Replaced water pump
Regularly replaced fluids and filters ( except tranny filter)
Replaced flex pipe in exhaust
Had split in Y-pipe (exhaust header pipe) welded.
Replaced washer reservoir bottle
Replaced radiator overflow bottle
Regularly replaced brake pads
Replaced all four struts
Replaced rear coil springs
Replaced tie rod ends
Replaced and repacked rear lower control arm boots.

 

OK. I'll answer my own post.

The dealer said there is NO problem using Lucas MultiVehicle synthetic blend tranny fluid, or any other SPIII tranny fluid.

I drained the tranny and filled with 5 quarts of Lucas Multivehicle synthetic blend tranny fluid. I've driven the car 15 miles since the fluid change and there is no 30-50mph shudder.

The magnetic drain plug had no large metal chips on it but did have a coating of what looked like black oil sludge. When I held another magnet nearby, it attracted the black stuff. So, very fine ferrous metal particulate had accumulated on the drain plug. My understanding is this is a normal part of transmission wear.

 

FWIW, this issue is pretty common in these cars. They burn up ATF badly.

It can be kept in check with extra-frequent ATF changes. MIne had this problem when I got it in '04 with ~40k miles. Dealer changed the fluid and it went away, so every time it comes back I just change (partial change - drain/fill) the fluid.

I usually see 10-12k between partial changes. On a full change (dealer flush) it generally goes twice as long before I notice problems.