what oil to use in a 1970 gmc with 402 bb?
- Thread starter gmc70
- Start date
- Status
Chevron Delo 400 is good too ,Good moly in it,
Mobil 1 15w50 if its nice and loose
If its fresh (rebuilt) .any quality 10w30 dino.
Any sludge probs?
What transmission? 4.11 rears I think.
Mobil 1 15w50 if its nice and loose
If its fresh (rebuilt) .any quality 10w30 dino.
Any sludge probs?
What transmission? 4.11 rears I think.
Last edited:
Did you flush the brake lines yet ,man I love those old finds.There's so much you can do 
"I've read many times that GMC BB's like their oil thick - during the summer, 20W-50 wouldn't be out of the question here."
I would agree. 15w-50, 20w-50.
I had a 68 C-10 1/2 ton with a 427 BB, Turbo 400 stock and it liked 10w-40 Valvoline. I also had a 69 Camper special 3/4 ton with dual overloads and heavy duty 10 ply tires with a 350 4 bolt main and a turbo 400. The 427 was much faster, but the 350 was perfect in that truck. I just hated the canister oil filter, getting that dang o-ring to seal.
Every oil change was like the James Dean gusher scene in the movie "Giant", you took a bath in oil.
A guy down the street had an orange and white 70 GMC with a 402 in it. It was a camper special with the faux wood tape on the side.
When you opened the glove box door on those trucks the build sticker was attached to the glove box door. It showed the engine and trans the truck came with along with some other specs. On the 68, I don't know how many times I had to prove to people that it came with a 427. Nobody would believe it did, but it did. The only thing it wouldn't pass was a gas pump.
I would agree. 15w-50, 20w-50.
I had a 68 C-10 1/2 ton with a 427 BB, Turbo 400 stock and it liked 10w-40 Valvoline. I also had a 69 Camper special 3/4 ton with dual overloads and heavy duty 10 ply tires with a 350 4 bolt main and a turbo 400. The 427 was much faster, but the 350 was perfect in that truck. I just hated the canister oil filter, getting that dang o-ring to seal.
Every oil change was like the James Dean gusher scene in the movie "Giant", you took a bath in oil.
A guy down the street had an orange and white 70 GMC with a 402 in it. It was a camper special with the faux wood tape on the side.
When you opened the glove box door on those trucks the build sticker was attached to the glove box door. It showed the engine and trans the truck came with along with some other specs. On the 68, I don't know how many times I had to prove to people that it came with a 427. Nobody would believe it did, but it did. The only thing it wouldn't pass was a gas pump.
15-40 or 20-50.
big heat and loads.
big heat and loads.
Just to change things up, I'd consider a 10W-40 HM oil like Valvoline MaxLife in summer, and 10W-30 in winter...
Checkout the build sticker inside on the glovebox door if it is still there. I think it shows the gear ratio? I know it show the engine and trans along with the GVW and payload capacity.
I also never cared for those having the gas tank inside of the cab.
Although they are possibly the easiest vehicle in the world to siphon gas from.
I also never cared for those having the gas tank inside of the cab.
Although they are possibly the easiest vehicle in the world to siphon gas from.
- Status
Similar threads
