Questions about OIL type ?

[alone]

1. What viscosity of motor oil should I use ?
.my repair book listed 10W/40 to 20W/40 but dang! aren't those kinda thick/heavy ?
My last oil change, I used 5W/30 though looking back, I should have gone with 10W/30

2. How about transmission fluid for a Manual transmission ?


BTW:
165K miles on my odometer

[wswilburn]

For motor oil viscosity, trust the manual. Different engines are designed for different viscosities. Sounds like you would be good with a 15W-40. Also, you need to know whether your engine has flat tappets or not. If it has hydraulic lifters, modern oils are good. If not (i.e. valves need periodic manual adjustment), it is a flat tappet engine and needs special oils with enough of a certain anti-wear additive to protect the camshaft. If this is the case for you, you can read this thread for more information Ultimate Motor Oil Thread or Why we hate CJ4/SM oils. There are various oils suggested. I get Swepco 306 from Pelican.

For transmission, see if there is a sticker on the side of it that says what kind of fluid to use. Could be ATF, lifetime fill, or regular transmission oil. For ATF, I use Mobil 1. For lifetime fill (a misnomer, replace at least every 100k miles in this case) I use BMW MTF-LT-2. For regular transmission oil, I use Redline MTL.