transmission fluid, which one?

I assume you are talking about a manual trans, not an automatic. Automatic transmissions use ATF like dextron, manual transmissions can take 75w90 gear oil or 10w30 motor oil depending on what year and manufacturer. Some manufacturers went to 10w30 to make it easier to shift especially in cold weather. Older vehicles of the 40's 50's 60's and 70's used heavy gear oil like 75w90. If my customer complained of hard to get in gear or shift, on cold mornings or when the temperature dropped we would change to a 20w50 or 10w30 motor oil. Hope this helps

Plenty of the manual transmissions had factory fill with ATF. Despite all the noise here you can use whatever weight you want. Back in the old days the gearboxes all used the 80W they could be quite stiff on a cold winter morning and switching to a lighter weight is perfectly fine. Note using a light weight oil or ATF in a transmission with marginal seals can leak out much easier and as i discovered on my jeep was not worth it.

10w30 is motor oil and you don,t want to use that in the transmission ! if it,s a manual you use either automatic transmission fluid or 90 weight gear oil, depending what kind of car it is !

Your options are not that simple:

Differential, Rear W/ TT......GL-5

All TEMPS......80W-140 [1]

SEVERE GEAR 75W-140 Synthetic EP Lubricant (SVOQT)

80W-140 Synthetic Long Life Gear Lube (FGO05)

Differential, Front W/ TT......GL-5

All TEMPS......80W-140 [1]

SEVERE GEAR 75W-140 Synthetic EP Lubricant (SVOQT)

80W-140 Synthetic Long Life Gear Lube (FGO05)

Differential, Front W/O TT......GL-5

All TEMPS......75W-90 [1]

SEVERE GEAR 75W-90 Synthetic EP Lubricant (SVGQT)

Differential, Rear W/O TT......GL-5

All TEMPS......75W-90 [1]

SEVERE GEAR 75W-90 Synthetic EP Lubricant (SVGQT)

Transfer Case,W/ MT......MA

Signature Series Multi-Vehicle Synthetic Automatic Transmission Fluid (ATF) (ATFQT)

Torque-Drive Synthetic Transmission Fluid (ATD1G)

OE Multi-Vehicle Synthetic Automatic Transmission Fluid (OTFQT)

There is more but that all I could fit in here.

Who told you to put oil in a transmission anyway???? Is this for a car or a tank?

What KIND OF CAR IS THIS THING??? automatics use AUTO TRANS FLUIDS< and MANUAL trannies use GEAR OIL and some use AUTO TRANS FLUID in them! Perhaps you are writng about REAR ENG OIL which is almost always GEAR OIL 75W-90. GIVE MORE DETAILS! 10W-30 is not used IN ANY TRANNY that I ever heard of! it is ENGINE OIL!

We need the year make and model of the car. Neither one of your chosen lubricants are for a modern transmission.

Calling for 75W-90.

Ya do not put 1030 engine oil in tranny..

Nor gear oil