Best Engine Oil for 307?

[BanjoDude]

Morning guys!

I recently bought a '69 C20 with a 307. I'd like to change the oil in the engine, transmission (3 on the tree) and rear end so that I know exactly what's in it and when it was changed. I use mostly Mobil products in my new stuff, but understand that these old engines like zinc, etc. What oil do you use and recommend for each of those components?

Thanks!

Wes

[68panelman]

I use Shell Rotella in all my old trucks, they still have the highest amount of zinc, 1200 ppm, 90wt for gears, sta-lube brand, right from Texas

[Getter-Done]

Mobil is a good brand.

This topic opens up a Big can of worms.

Especially when you're talking to old guys (Like most of us on the Forum)

Do you use Conventional or Synthetic in older vehicles?

Then the fight begins

Here is a forum in the link below,
That my brother reads that has lots of advice and Opinions about oil.

Link: https://bobistheoilguy.com/

[Grumpy old man]

I use Castrol GTX Classic 20W-50 Conventional Motor Oil in my 67's small block and my 95 k2500 engines , Driven brand gear oil in the Muncie 4 speed and posi rear differential The posi requires additive . . Use the type oil whatever engine you have that it was designed to use when new , Never use synthetics in a classic car/truck .

https://www.amazon.com/Castrol-Class...09QXWLY2Y?th=1

https://drivenracingoil.com/i-304977...SABEgKgq_D_BwE

[Yamariv]

Originally Posted by Grumpy old man

I use Castrol GTX Classic 20W-50 Conventional Motor Oil in my 67's small block and my 95 k2500 engines , Driven brand gear oil in the Muncie 4 speed and posi rear differential The posi requires additive . . Use the type oil whatever engine you have that it was designed to use when new , Never use synthetics in a classic car/truck .

https://www.amazon.com/Castrol-Class...09QXWLY2Y?th=1

https://drivenracingoil.com/i-304977...SABEgKgq_D_BwE

OP, just did all this to my truck. Only thing you really need to pay attention to for oil is the transmission. You have brass syncros in your 3 speed, make sure you get a GL4 (ONLY) oil that is safe for brass syncros.

The rest of the oils and brand is prefference..

[BanjoDude]

Originally Posted by Grumpy old man

I use Castrol GTX Classic 20W-50 Conventional Motor Oil in my 67's small block and my 95 k2500 engines , Driven brand gear oil in the Muncie 4 speed and posi rear differential The posi requires additive . . Use the type oil whatever engine you have that it was designed to use when new , Never use synthetics in a classic car/truck .

https://www.amazon.com/Castrol-Class...09QXWLY2Y?th=1

https://drivenracingoil.com/i-304977...SABEgKgq_D_BwE

I k ow this is likely a stupid question, but how can I tell if I have a posi diff? Would the report from George Zapora tell me that (attached).

[Warrens69GMC]

how do you get in touch with George Zapora? I need to find out what mine came with.

[Stocker]

Originally Posted by BanjoDude

I k ow this is likely a stupid question, but how can I tell if I have a posi diff?

The only stupid question is one you don't ask.

Park on level ground, chock the front tires, put trans in neutral, and release the parking brake.

Jack up the rear until both rear tires are off the ground. Manually rotate either rear tire.
If the opposite side tire rotates in the same direction, you have a posi.
If it rotates in the opposite direction, you have an open diff.

['68OrangeSunshine]

Originally Posted by BanjoDude

Morning guys!

I recently bought a '69 C20 with a 307. I'd like to change the oil in the engine, transmission (3 on the tree) and rear end so that I know exactly what's in it and when it was changed. I use mostly Mobil products in my new stuff, but understand that these old engines like zinc, etc. What oil do you use and recommend for each of those components?

Thanks!

Wes

Valvoline Racing Oil VR1 SAE 30.

[Getter-Done]

Originally Posted by Warrens69GMC

how do you get in touch with George Zapora? I need to find out what mine came with.

Keith gave the info in post#9 of this thread

http://67-72chevytrucks.com/vboard/s...=George+Zapora

[Grumpy old man]

Originally Posted by Yamariv

OP, just did all this to my truck. Only thing you really need to pay attention to for oil is the transmission. You have brass syncros in your 3 speed, make sure you get a GL4 (ONLY) oil that is safe for brass syncros.

The rest of the oils and brand is prefference..

Well ... This old guy is going to have to disagree with you . if you start dumping any synthetic oil in your 50 year old truck your going to find oil leaks you never had before , The engines weren't designed to use them . Use conventional oils (The dinosaurs are already dead , Your not saving the earth or your engine )

Watch this video it may help .

https://www.youtube.com/watch?v=atjO_2DH3GQ

[Warrens69GMC]

Originally Posted by Getter-Done

Keith gave the info in post#9 of this thread

http://67-72chevytrucks.com/vboard/s...=George+Zapora

I should read the threads completely

[kwmech]

I just get the Napa oils and use some Lucas as an additive. Been no complaints from any of my engines. Even do the same in my wifes KIA. Service manager approved at the KIA dealer for warranty purposes since the engine has the VVT system

[Myself]

Obviously you need to run Pennzoil.......that way it blows up quicker and you can promptly yank that gutless wonder and replace it with a real man's truck engine, LOL!

[Getter-Done]

Originally Posted by Myself

Obviously you need to run Pennzoil.......that way it blows up quicker and you can promptly yank that gutless wonder and replace it with a real man's truck engine, LOL!

This was his Grandpa's truck.
He probably likes it just the way it is.

[jumpsoffrock]

Originally Posted by Grumpy old man

Well ... This old guy is going to have to disagree with you . if you start dumping any synthetic oil in your 50 year old truck your going to find oil leaks you never had before , The engines weren't designed to use them . Use conventional oils (The dinosaurs are already dead , Your not saving the earth or your engine )

Watch this video it may help .

https://www.youtube.com/watch?v=atjO_2DH3GQ

People scared me with this "engines weren't designed for it" for a long time.

I rebuilt my 1956 Ford 223 inline 6 in 2010 and was originally going to switch over to synthetic after 5-10k miles, but I never did.
In 2019 the engine was on it's last leg for several reasons not relevant to this thread, but what is relevant is that it was burning no oil, and it was leaking like a seive at the rear main seal, and had been suffering from low oil pressure.

I remember being taught in school that synthetic oil is more resistant to breakdown by overheating, and can often maintain more consistent pressure characteristics, so with a dying engine with low oil pressure, leaking RMS, and 50k miles, I switched from 20W-50 conventional to 20W-50 Mobil 1 full synthetic.

RMS leak was noticeably less right off the bat, no oil burning, NOT A SINGLE DROP of oil from any other previously-not-leaking-seal, and my pressure went up 5-10 lbs across the board. And all these improvements remained for about 5k miles until I put the engine out of its misery.

In 2010 I also switched my 185k mile Honda Prelude from conventional to synth with zero oil leaks. all oil seals were original.

All this myth about it being detrimental to switch old/high mileage engines to synthetic is hooplah.



Everybody has their stories, these are mine.

[Steeveedee]

Originally Posted by Myself

Obviously you need to run Pennzoil.......that way it blows up quicker and you can promptly yank that gutless wonder and replace it with a real man's truck engine, LOL!

And use a Fram filter, amirite?! I see people slamming those all the time, but I've never had an oil-related failure after decades of using them.

As for Pennz, I remember a friend of my dad's had a '56 Chevy wagon that he only used non-detergent oil in, and replaced it as needed. In retrospect, I was pretty young, so I didn't notice if it had the optional oil filter. Anyway, he was working on it, and had the intake manifold and valve covers off. I distinctly remember that the oil had congealed like jello around the rocker arms, and there was a whole lot of it in the lifter galley. He was scooping it out with his hands. My dad used Havoline, and there was never anything but an oily surface when an engine was opened up around our place.

[Getter-Done]

Originally Posted by Steeveedee

And use a Fram filter, amirite?! I see people slamming those all the time, but I've never had an oil-related failure after decades of using them.

As for Pennz, I remember a friend of my dad's had a '56 Chevy wagon that he only used non-detergent oil in, and replaced it as needed. In retrospect, I was pretty young, so I didn't notice if it had the optional oil filter. Anyway, he was working on it, and had the intake manifold and valve covers off. I distinctly remember that the oil had congealed like jello around the rocker arms, and there was a whole lot of it in the lifter galley. He was scooping it out with his hands. My dad used Havoline, and there was never anything but an oily surface when an engine was opened up around our place.

I remember the Big deal Quaker State went thru with that gel/sludge stuff .

[truckster]

Originally Posted by BanjoDude

I k ow this is likely a stupid question, but how can I tell if I have a posi diff? Would the report from George Zapora tell me that (attached).

You do not have a posi unless it was added later. If it came from the factory with one it would be on the SPID.

[chevmn]

Originally Posted by BanjoDude

I k ow this is likely a stupid question, but how can I tell if I have a posi diff? Would the report from George Zapora tell me that (attached).

G80 Positraction Rear Axle would be listed. Believe me, if you used regular gear oil in a posi, you would likely know it fairly quickly as the clutches would begin sticking in turns (ask me how I know this). I simply add the additive in that case on the older posi units. Most of the newer G80 units are a ratcheting type, and really do not need the additive, but I also do not like as they release too quickly (my opinion).

Keep in mind most any of todays oils are likely better than any of the older oils. It is getting difficult to even find conventional oils, but I have been buying the Traveller oils from Tractor supply (good oil). I have a vehicle with over 400,000 miles running the conventional Warren oil (TSC, WalMart), and no issues. I used to only run name brand oils. I do shy away from Fram filters (never had any issue, but bad reviews scared me away).

[Steeveedee]

Originally Posted by Getter-Done

I remember the Big deal Quaker State went thru with that gel/sludge stuff .

Well, yeah, but he only added as necessary, with the non-detergent stuff. That's asking for it. I remember in '71 working for a Chevy dealer and a '70 Camaro came in with some sort of noise. It had a ton of miles on it, and when that tech pulled the valve covers, it was like that '56 Chevy. Thing is, the owner couldn't provide proof of ever changing the oil. Proof for never changing it was right there in the jello. Warranty void. I bought a new car 6 years ago. I just take it to the dealer for oil changes every 6 months, because I don't drive it all that much, as I'm retired. That's their requirement. It's about $150 a year for maintenance on it, and anything that goes wrong falls on the dealer. Back when I was working for a living I changed the oil in my commuter car every 6 weeks, which was 3000 miles. It got to 230+k miles before I sold it.

[special-K]

Mel, if you are asking what brand or type of oil, any quality brand you like is good. Pretty much the same with type since it's nit a high rpm screamer. As far as weight, I also use 20w50 because it stays in an older motor best, leaks or burning. Pour weight of 20w sounds heavy by new and modern car standards, but back when these trucks were built most people ran 20w straight in winter and 30w straight in summer. You can run in the 307 whatever is good for any small block. For economy I run Walmart 20w50 in my daily driver with 350 because it used to have an oil consumption issue. In a truck with a healthy small block I want to treat special I run Castrol GTX. It will keep rings nice and freed up with the castor oil it has in it

Originally Posted by Myself

Obviously you need to run Pennzoil.......that way it blows up quicker and you can promptly yank that gutless wonder and replace it with a real man's truck engine, LOL!

Some don't need a bigger engine to feel like a man . My experience has been 307s are a long lasting. They don't want to blow up. I figure his 307 could be 53 years old and hasn't blown up yet because nobody rebuilds them, right? That is the common mentality. Well, except me. I rebuilt one because it threw the crappy fiber geared timing chain, bent push rods and a valve or two. A few changes and I had myself a strong running 307 that got fuel economy a 350 couldn't touch. GM never built a performance 307 but that doesn't mean we can't. After all, it's a Chevy/GMC small block

[Steeveedee]

Oil is oil, up to some kind of weird point. I used to flip Chevy Vegas, and was a real fan of Castrol in those days. I sold one to my FiL, but it used oil like a big dog, like a quart every 500 miles, even though it was rebuilt. He sold it to one of my wife's friends when he got a screaming deal on an AMC Gremlin. My wife's friend had Pennz put in it at her first oil change and it never used a drop after that. I have no answer for that.

[BanjoDude]

Originally Posted by Getter-Done

This was his Grandpa's truck.
He probably likes it just the way it is.

That's a fact. He was an auto mechanic for 59 years. I have some of his tools, and the powertrain is completely original - never rebuilt - so I plan to keep it just like it is. I love power as much as the next guy, bit there's something kinda cool about working on his old truck with his old tools.

[special-K]

Originally Posted by BanjoDude

That's a fact. He was an auto mechanic for 59 years. I have some of his tools, and the powertrain is completely original - never rebuilt - so I plan to keep it just like it is. I love power as much as the next guy, bit there's something kinda cool about working on his old truck with his old tools.

Sounds perfect and it's great you appreciate the truck as you do

Originally Posted by Steeveedee

Oil is oil, up to some kind of weird point. I used to flip Chevy Vegas, and was a real fan of Castrol in those days. I sold one to my FiL, but it used oil like a big dog, like a quart every 500 miles, even though it was rebuilt. He sold it to one of my wife's friends when he got a screaming deal on an AMC Gremlin. My wife's friend had Pennz put in it at her first oil change and it never used a drop after that. I have no answer for that.

My story goes to show your first statement is correct, because I had a completely opposite experience. When I took my '71 Custom Camper rig out west in '89 with my dad and my son I had a scare. The truck was using oil badly, like a quart, at least, at fill-up, which was about 120 miles. I considered turning back for home. Back then I had been running Pennzoil Racing Oil in all my trucks with no issues, felt real good about it. My dad, at that time, was doing fleet maintenance for a handicap help center that ran a bunch of vans. He suggested running some Castrol in it because he had success with it freeing stuck rings in something he was maintaining. He said it was all about the castor oil. I only half listened to him while I was checking it over on the lot of a truck stop. I look up and see him walking back to the truck with a couple quarts of Castrol. WTH, I poured it in. It needed some kind of oil no matter what. I reluctantly carried on with heading west and with each fuel stop it used less until it kept it stopped needing more. We made it out to Taos, up into the Rockies, Mesa Verde, 4-corners, Painted Desert, north Rim of Grand Canyon, and on down to Flagstaff. I had the oil changed there before heading back. I was disappointed to see they used Quaker State. But I used that before I switched to Pennzoil. I was taught back when I started driving that PA grade oil was the best, but that became old info at a point since. Once back home the oil pressure read noticeably lower. I changed it with Castrol and that's what I ran in it till '04 when I parted it out. That original 350 never needed work except a timing chain and at that time did the heads to work with no-lead. I still have that engine on a stand, could be dropped in something else if needed.