Oil Choice for Jeep AMC 304

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Changing the motor oil in my CJ-7, stock 304 V-8 with about 38k original miles. Vehicle may see about 750 miles/year. Which oil and why?

Choices in my stash are:

1) Smitty's SuperS 5W-30 syn/blend GF-5/SN
2) Mobil Super 10W-30 GF-5/SN
3) Valvoline Syn Power 5W-30 GF-5/SN/Dexos-1
4) M1 EP 10W-30 GF-5/SN

Please let me know soon, want to knock this out before the Masters coverage starts. TIA
 
Of the oils you've listed I'd use the 10w30 Mobil conventional. The EP would be a waste since you probably would need to change it every 2 years....which is only 1500 miles. I'm sure the OM calls for a 10wXX since I don't believe 5wXX oils were available in 1979..
 
Originally Posted by Egg_Head
Changing the motor oil in my CJ-7, stock 304 V-8 with about 38k original miles. Vehicle may see about 750 miles/year. Which oil and why?

Choices in my stash are:

1) Smitty's SuperS 5W-30 syn/blend GF-5/SN
2) Mobil Super 10W-30 GF-5/SN
3) Valvoline Syn Power 5W-30 GF-5/SN/Dexos-1
4) M1 EP 10W-30 GF-5/SN

Please let me know soon, want to knock this out before the Masters coverage starts. TIA


None of the above. Your Jeep with it's AMC 304 is prone to timing chain and front cover oil pump wear reducing oil pressure and changing cam timing as the chain wears. Not to mention the flat tappet cam and lifters.

Use an oil better suited for a flat tappet engine. Many are out there, any CI-4 or 4+, CJ-4, CK-4 (in CK4 look for an oil without an SN rating) in 10w30 or 15w40. Valvoline, Mobil 1300 Delvac, Super Tech, Traveler's from TSC are all great options.

I would not run a passenger car oil in your Jeep, go for the extra protection of a HDEO.
 
Originally Posted by FlyNavyP3
Originally Posted by Egg_Head
Changing the motor oil in my CJ-7, stock 304 V-8 with about 38k original miles. Vehicle may see about 750 miles/year. Which oil and why?

Choices in my stash are:

1) Smitty's SuperS 5W-30 syn/blend GF-5/SN
2) Mobil Super 10W-30 GF-5/SN
3) Valvoline Syn Power 5W-30 GF-5/SN/Dexos-1
4) M1 EP 10W-30 GF-5/SN

Please let me know soon, want to knock this out before the Masters coverage starts. TIA


None of the above. Your Jeep with it's AMC 304 is prone to timing chain and front cover oil pump wear reducing oil pressure and changing cam timing as the chain wears. Not to mention the flat tappet cam and lifters.

Use an oil better suited for a flat tappet engine. Many are out there, any CI-4 or 4+, CJ-4, CK-4 (in CK4 look for an oil without an SN rating) in 10w30 or 15w40. Valvoline, Mobil 1300 Delvac, Super Tech, Traveler's from TSC are all great options.

I would not run a passenger car oil in your Jeep, go for the extra protection of a HDEO.



No it will not have additional benefit from old additive technology on a stock engine.
 
Completely and utterly disagree.

Does it have high valve spring pressure? No. It doesn't.

However to say that there's absolutely no benefit from increased AW additives is not at all true. Those AW components benefit the cam, lifters, sled type rocker arms, valve tips. All wear areas that aren't present in modern day roller valvetrain.

There's certainly no detriment to running a HDEO and plenty of argument for benefit based on the AMC engine architecture.
 
Originally Posted by FlyNavyP3
Completely and utterly disagree.

Does it have high valve spring pressure? No. It doesn't.

However to say that there's absolutely no benefit from increased AW additives is not at all true. Those AW components benefit the cam, lifters, sled type rocker arms, valve tips. All wear areas that aren't present in modern day roller valvetrain.

There's certainly no detriment to running a HDEO and plenty of argument for benefit based on the AMC engine architecture.



You can disagree but your argument isn't correct.
 
I'm in the camp that would run a 10W-30 or 15W-40 HDEO before a thinner ILSAC oil.

An old engine like that needs a bit more viscosity that the HDEO offers.
 
Originally Posted by dave1251



You can disagree but your argument isn't correct.


Care to explain how the extra AW provided by a HDEO wouldn't benefit? You've provided no basis for your opinion and furthermore added nothing to the discussion.

Ford feels strongly enough about Phosphorus content in their ONE and only pushrod engine currently in production to state that 1,000 ppm or better is required to provide adequate valvetrain protection. It also is stock, low revving, low spring pressure.

Additionally the added HTHS of the HDEO is beneficial to the AMC and Buick engines that suffer from oil pump wear in the aluminum timing cover.

I encourage you to add something to the discussion instead of re stating your dissent over and over again with no basis.
 
10w-40 or 15w-40. Lots of clearance in AMC motors. The 10w-30 Mobil if you have to run something out of your stash, and it will be fine.
 
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Of the choices listed, #2, but am also in the camp of a 15w-40 HDEO.

But for the little it is driven, any of them would probably be fine for a 2 year interval unless those 750 miles are hard core off-roading (which from the condition of the Jeep is not the case).

Looks nice BTW.
 
Originally Posted by c502cid
10w-40 or 15w-40. Lots of clearance in AMC motors. The 10w-30 Mobil if you have to run something out of your stash, and it will be fine.

Thanks everyone for the input, 10W-30 went in. Sounds like I need to get something more stout for the next oil change. Masters is heating up!
 
I had a IH Scout with a 304. It ran on SAE 30. Havoline was my choice then. The engine was not the same as yours but the similarities confused a lot of people back then.
 
Originally Posted by PimTac
I had a IH Scout with a 304. It ran on SAE 30. Havoline was my choice then. The engine was not the same as yours but the similarities confused a lot of people back then.

Yep. Only thing they share is the coil wire.
 
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