71 340 OIL CONVENTIONAL/SYNTHETIC

[gf7cuda]

Hello Mopar friends. Just in need of a little advice. I ran my 340 engine on engine stand to break in and all is good. Looking for advice to use conventional oil or synthetic moving forward. Also what weight / viscosity. Thanks in Advance....Bill.

 

[resronut]

Use high zinc oil only unless roller cam and clearances built for synthetic.

 

[gf7cuda]

Use high zinc oil only unless roller cam and clearances built for synthetic.

Thank you...no roller cam, all stock.

 

[gf7cuda]

Use high zinc oil only unless roller cam and clearances built for synthetic.

10w30 ? That's what I usually use.

 

[Xcudame]

Where are you located? 10W-30 will work fine, but down here in the desert, I like something a little thicker, straight 30 weight or 20W-50.

 

[Chryco Psycho]

Joe Gibbs or Brad Penn make oils designed for flat tappet engines , agricultural oils are rated SJ which is the right formula , I usually used 10-40w but the zinc/ ZDDP content is far more important than the weight of the oil used .

 

[Challenger RTA]

When I did my break in. It ran 20 - 30 min for the break in and ZDDP. Then I had it run another half hour mostly at an oscillating idle. Drained oil and cut filter and inspected.
Refiled with break in oil , ZDDP and new filter.
Restarted engine and idle fine.
From what I understand, It is recommended to run 500 miles with break in oil. If not the rings will not seat or bed properly. Need to be accelerating and decelerating so the rings to seat. In short thrust on the rings and cylinder wall.

 

[Xcudame]

Really, with STP oil treatment and the cheapest oil out there would work. The main thing is the extra zinc and phosphorus. And the proper brake in mentioned above.

 

[gf7cuda]

Where are you located? 10W-30 will work fine, but down here in the desert, I like something a little thicker, straight 30 weight or 20W-50.

Mass , thanks for info

 

[gf7cuda]

Joe Gibbs or Brad Penn make oils designed for flat tappet engines , agricultural oils are rated SJ which is the right formula , I usually used 10-40w but the zinc/ ZDDP content is far more important than the weight of the oil used .

Thanks Chryco. Appreciate it

 

[gf7cuda]

When I did my break in. It ran 20 - 30 min for the break in and ZDDP. Then I had it run another half hour mostly at an oscillating idle. Drained oil and cut filter and inspected.
Refiled with break in oil , ZDDP and new filter.
Restarted engine and idle fine.
From what I understand, It is recommended to run 500 miles with break in oil. If not the rings will not seat properly. Need to be accelerating and decelerating so the rings to seat. In short thrust on the rings and cylinder wall.

Good stuff RTA. ...looks like if there is break in oil with the zink I'll be good. I'll check if Gibbs or Penn makes it. Appreciate it

 

[gf7cuda]

Really, with STP oil treatment and the cheapest oil out there would work. The main thing is the extra zinc and phosphorus. And the proper brake in mentioned above.

Yea looks like the break in for another 500 miles is crucial. I will look at the Gibbs, Penn and Stp options with the zinc. All you guys have been helpful Thanks

 

[Moparbastard]

Use only mineral oil - Driven brand with zinc for flat tappets. With roller cam you can use any mineral oil. My machine shop says synthetics are too be avoided on these old engines.

 

[gf7cuda]

Use only mineral oil - Driven brand with zinc for flat tappets. With roller cam you can use any mineral oil. My machine shop says synthetics are too be avoided on these old engines.

Thank you, all stock so I will be looking for Driven, Gibbs, Brad Penn, with zinc/ mineral oil. For my flat tappet 340. Appreciate this information

 

[brotow]

Rotella oil is ideal for older cars without catalytic converters and for which zinc was a requirement at the time for engine oil. It eliminates the need for adding a zinc additive to modern oils.

 

[Moparbastard]

Rotella oil is ideal for older cars without catalytic converters and for which zinc was a requirement at the time for engine oil. It eliminates the need for adding a zinc additive to modern oils.View attachment 123102

Sadly, Rotella no longer has sufficient zinc and phosphorus additives for use with flat tappets. Also little packets or bottles of ZDDP additives don't work either. Driven brand oil is the best for flat tappet cams. Lucas and Brad Penn also make such an oil. There may be other brands. The new flat tappets are mostly defective due to having the faces ground incorrectly. If you can find NOS or NORS lifters it would be best or go with a roller cam.

 

[Avalanche]

Hello Mopar friends. Just in need of a little advice. I ran my 340 engine on engine stand to break in and all is good. Looking for advice to use conventional oil or synthetic moving forward. Also what weight / viscosity. Thanks in Advance....Bill.

Who rebuilt your engine?
Was it do e in Mass?