3rdrjc

When to use OD , when to use regular D

JimLentz

Unless you're towing or need/want to use engine braking use OD.

confab

Trans is a little stronger in "D" Coast clutch backs up the forward sprag (engine brake) and you get a little line pressure bump.

VikingTrad3r

im probably alone here, but i drive around in 2, and if i need to i bump it up to D. only ever on OD when im on the hiway. my L98 is anemic enough and i find i get much better torque up higher in the rpm.

colo63sw

I read this once written by a trans technician.

If you are driving in the city, keep it in D. Going between stoplights, running through the gears and the trans shifting into OD at the bottom of OD range, and driving near the bottom of OD range puts a strain on the trans. In city driving that cycle gets repeated time & again.
City driving ‘D’; extended periods of 40mph+ driving use ‘OD’.

He may be wrong. I’m just relaying the message, but it made sense to me.

confab

Yeah, that is correct. You shunt the sprag in D, and you get a PSI bump in the lower manual select gears.

And yeah, very few people do realize that. If they saw the sprag they would never, ever believe that little piece of metal bears the entire weight of their vehicle.

I used to keep one in here to show customers who complained because "the kit" is only 300 bucks or so. What they're missing is the importance of hard parts like that sprag.

TA

I use "D" at all times except when I get on the highway.

A Peter C4

I stay in D unless at least 48 mph as that's when it will shift into OD on its own, I usually shift into OD at 50 mph or above. Converter lockup occurs when at that speed in my 94 LT1 Coupe. I do not like to create alot of trans temp with converter slipping at low speeds when trans is hunting for correct gear. When slowing down I drop to D at about 40 mph and 2 at about 28 mph, same on upshift and have had no problems. Fuel mileage is not a big concern to me.

aklim

If I see it hunting, I drop it into D.