Hi Guys,

1984 230TE: after leaving the car overnight when it's cold outside (10-40F) the transmission shifts incredibly hard . . . almost feels like someone's hitting the car from behind. After it warms up, it shifts fine. Other than the typical fluid and filter change anything I can check for? Also, what's the consensus on synthetic gearbox fluid for these older cars?

Second, per my dad's (apparently lame) advice I tried using some Prestone stop leak in the cooling system. I was getting a faint smell of coolant (prolly a small leak in the heater core) when the heat was on so I figured I'd give this Prestone crap a shot. Well, as you can imagine it didn't work and now the car runs much hotter than before. Somewhere about 105-110C cruising on the highway. Again, I'm going to flush the system, but could I have messed up anything else?

Thanks a stack,

Paul