305 V-6 engine oil
 

Hello I'm new to this group.My wife and I just purchased a 1965 GMC C-15 with the 305E V-6 in it.We are going to restore it.We want to keep this motor in it.I'm curious what kind of oil everyone is running in there 305's ? What is the oil canister filter number you running? Thanks I advance.

Re: 305 V-6 engine oil
 

Congratulations on your purchase, MM! If you treat it right, it should outlast you. These engines are capable of going over a half million miles with the right preventative maintenance. Oil changes are number one. Regarding what kind of oil, you'll get a variety of answers since everyone has their favorite. I've always used Amsoil 10W-40 synthetic oil.

My trucks use the spin-on filters, and I don't remember what the cartridge filter number is any more. I'm sure someone on the forum here can help with that though. By the way, C-15 (C-20 in your ID) is a Chevy type of model number. If your truck is a half ton, you have a model 1000. If it's a three quarter ton, you have a 1500.

We're looking forward to learning more about your truck, and seeing some photos of it.

Re: 305 V-6 engine oil
 

The napa p/n for the 1 qt filter is 1121. And as long as you are happy with the brand of oil you like to use, just make sure the oil has plenty of zddp in it. Modern oils don't have enough to protect the camshaft & lifters.

Re: 305 V-6 engine oil
 

Sorry never owned this year truck before.The guy we purchased it from had it listed as a C-20.After I ran the Vin. it said C-15. It is a 3/4 ton.I'm a firm believer in keeping up on oil changes so I hope it holds up.Once I figure out how to post pics I well share .Thanks

Re: 305 V-6 engine oil
 

I edit my description and added a few pics. She runs good and the body is solid.We have some dents to bang out. Also have a few patch panels to replace in the front lower front fenders and replace the roof skin..

Re: 305 V-6 engine oil
 

Use our VIN decoder page. Go to "jolly's......page" at top left. Click on "VIN Numbers" in the colored menu. Scroll down and read. As said "C" means Chevrolet. If the decoder you used said C-15, it's a Chevy decider or a bad decoder. We have the official.:rowdybeer:

you will have a 1502xxxxxxx............if you don't, better let us know what it is.

Re: 305 V-6 engine oil
 

Lewis is correct -- you definitely need to use a high ZDDP oil. That's why I like https://www.amsoil.com/p/z-rod-10w-4...motor-oil-zrd/.

Note that it says "High-zinc formula protects flat-tappet cams, lifters, rockers & other critical components".

Re: 305 V-6 engine oil
 

I use Valvoline VR1 10W-30. Amsoil is good too. The Zinc/ZDDP additive is more critical in an engine with new flat-tappet cam and lifters, but why take a chance in an engine with a lot of miles on it?

Re: 305 V-6 engine oil
 

Okay sorry I've only owned old Chevys before .I knew the C 's were 2 wheel drive and K's were 4 wheel drive.It is a 1500 GMC .There is no C before it.Thank you for clarifying.

Re: 305 V-6 engine oil
 

I'm using Shell Rotella T1 Straight Grade SAE 30.

Re: 305 V-6 engine oil
 

I have used Valvoline VR1 high Zinc 30W and 20W50 conventional and 80W90 in transmission and rear end Louie Louie has 305E, 420SM ,307 diff. OE cannister oil filter part # CH106PL all from AutoZone. Good days with your GMC. JF

Re: 305 V-6 engine oil
 

I use Valvoline VR1, it's easier to find while traveling on the road.

Re: 305 V-6 engine oil
 

I believe Valvoline VR1 is what we will be using.Still in disassembly stage.We haven't pulled the engine yet.I'm going to miss firing her up and hearing her run. We just recieved all gasket sets needed so motor will be gone through soon hopefully.Still have to order me a canister oil filter.Thank you all for info.