Two car questions I’ve always wondered about...
 

1. In an automatic transmission car. When stopped, does it harm the transmission to put the car in neutral?

2. When using fuel system cleaner (Techron/STP) is it better to run it through the engine before you do an oil change or after?

I’ve always wondered about the two questions above. Curious what the Pelican brain trust thinks...Thanks.

1) Not really. I had to do that in a car with idle issue years ago as it takes load off the engine (doesn't have to turn the torque converter).

2) I don't think it matters.

1) Some transmissions do not cool the trans fluid in neutral. If the brake rotors are overheated, putting it in neutral and releasing the majority of the applied brake pressure might prevent warping. Idle issues aside, no reason to put it in neutral.

2) Old school said that Techron should be prior to oil change. Idea was that soluable dirt and gunk would migrate to the oil. I guess past rings, valve seals, PCV...

Maybe our oil doc, Holloway could chime in.

I thought it would get burned up and/or pushed out the exhaust.

don't know much about tranny's but I thought if the oil pump is working oil would still go thru the oil cooler. not sure why it would not.

re question 2 I'd go with 'right before an oil change'.

iirc one of the high end fuel treatments (44k or something like that) might even suggest an oil change after.

What’s an “automatic transmission”?

;)

Shouldn't harm the transmission at all. Usually the pump is on the main input shaft. As long as the engine is spinning, that pump is pumping.

1) no - 2) doesn't matter

1) as long as the engine is running, the trans fluid is being circulated, pressurized and cooled.

2) most fuel cleaners/ additives are largely alcohol. A few exceptions are GM Top Engine Clean & BG 44 which are designed with the professional technician in mind.

1. no...if so, i figured idling the car in PARK would suck as well.

2. i know folks that ONLY run chevron fuel in their cars. it has techron in it full time..that would sully the oil change regiment..no? or is it a matter of dosage?

gah..i need to get off my ass and do some car maint before my long long loooong drive. next weekend.

Does Chevron premium have more Techron than regular? I heard it used to- don't know if that's true anymore.

I think that you might be overestimating what Techron, (or other fuel additives), can do. They might clean you injectors and fuel system somewhat, (-might-), but whatever they are cleaning would surely get burned along w the fuel it is diluted in, I would think.

Fuel and oil additives definitely can work, I've had great luck w ATF or Seafoam in crankcases freeing-up sticky hydraulic lifters and rings, for example.

Great to see you here, BTW! SmileWavy

Any opinion on ATF or Seafoam vs SWEPCO 502 Premium Engine Oil Improver

Completely different things. That Swepco product is an additive package that you add to your exiting oil and ATF or Seafoam is more of an enema, just a super detergent to run through and then change your oil soon after.