2002 SC430 with 190,000 + miles. Transmission slipping when cold. Only 1st and 2nd gears. After it warms up, it's fine in all gears. Fluid level is on the mark. Should I take it to a trans shop or start looking for a replacement tranny?

 

Your looking at only a couple of things at usually cause this behavior. One fluid level is low, and it expands when heated to raise the level.

Two denatured, or dirty fluid fluid. If this is the case a filter and fluid change should solve the issue.

If the the problem was the other way around (slips when hot). I'd be looking at a new or getting the trans rebuilt. Don't let your current issue go on until it does cause damage though.

 

Is fluid and filter change something I can do myself? I'm pretty sure it's not low level. It starts shifting properly after about 300 - 400 feet.

 

There's threads on filter change and fluid change. bgw70 I know has one on fluid change. It's not that difficult. The pan drop can be messy though.

While ia was in there I would do the shift mod too.

 

What's the shift mod?

 

https://www.clublexus.com/forums/sc4...0-a-650-e.html

 

When I lived in a cold climate (Detroit) and we had a vehicle with high mileage come in with this concern...99 out of a hundred times the cause was hardened clutch pack piston o rings. The excessive internal trans heat makes the seals hard and brittle. After a few minutes when the fluid heats up, the o rings soften a bit to seal and apply the clutch pack.
There was a product available one time called 'seal softener' to use as a band aid to help overcome this concern. It basically was a trans fluid with some brake fluid added. I know brake fluid in an auto trans sounds scary, but this did help high mileage transmissions cure the slipping when cold concern.

 

This fix I am talking about is not a shift concern, but an engagement concern. In other words..for a delay when engine is first started after a while and you have to wait for trans to go into gear.