Greetings
I have a great 91' 740
with 250,000 kilometers
1 any thoughts on Lucas oil stabilizer, will it do any good?

2 my last muffler the last one in the car, will need to be replaced soon
any thoughts any brands to avoid, any great ones?

3 I plan to get the valves adjusted, also debating on the timing belt, @ 250k, I know it wouldn't hurt to have it changed, I bought it with 240k and not sure when it was last changed, the question is, is there any correlation, I think, think and think, but am not surewill one have any effect on the other,
can I get the valves done, and then change the belt at a later date????

4 it is strange, automatic/the tranny seems to have a mind of its own
when I drive agressively it changes fairly smooth
if I use a soft foot it seems to shift quite rough, is this normal?????
is it possible to change shft points
at times it shifts smoothly, sometimes it shifts quite roughly

thanks so much for any pointers you may have for me