426 Hemi oil viscosity

68HemiCharger · May 10, 2021

I still don't have an owners manual for my recently acquired 1968 Charger 426 Hemi. Stock all original engine. What is the reccomended oil viscosity? I'm seeing many people saying 10-40, 15-40, 20-50. What does the manual say?

Yes I will be running a Zinc oil.

91r/t · May 10, 2021

I myself run 10w40 full synthetic in all my big blocks and small block. The thought process behind 20w50 is keeping a decent oil pressure and oil film on bearings when the clearances have been machined loser for racing purposes. Quite honestly you will get all kinds of answers as this topic will always be up for discussion with 1,985 different opinions, but if you have to run 20w50 in your big block to keep it from leaking oil or keeping decent oil pressure and you run it street only, you have other issues. Hell, my new Johnson lifters only recommended 10w30 or lighter oil for them right on the box and they are just a standard flat tappet hydraulic lifter. I don't see why you can't run a good 10w30 or 40 in that engine with a good zinc rating like Amsoil or some others have and have no issues what so ever. I am sure you won't be out there winding it to 7K RPM's down the quarter mile. Enjoy that beautiful ride man!

:thumbsup:

AR67GTX · May 10, 2021

I run 15W-40 Rotella (diesel) Dino oil in most of my old cars and it has higher zinc levels. I have run 15W-50 Joe Gibbs Dino oil (HR) if I need it to maintain 20 psi idle oil pressure on a hot engine. The owners manual won’t do you much good as it represents 50 year old oil technology on a factory built engine. Your engine may likely have been rebuilt over the years.

Runcharger · May 10, 2021

I have always run 10-30 or 10-40 in my street hemis since 1980. In my mind it is important to have a light enough oil to flow through on a cold start.

Challenger340 · May 10, 2021

The Engine Oil Pressure exhibited by the Engine itself .... across the full range of Temperature and RPM's.... should dictate what Oil weight should be used in the particular Engine.

So is this an UN-Rebuilt... NEVER Touched or redone Engine ?
Because if it is....
it matters NOT whatever weights of Oil were Rec'd in the manual "Back in the Day"....
because all the Oil additive Pkgs have changed dramatically since that period..... meaning reference my original statement and let the Engine tell you what weight of Oil it wants..... the only Caveat being whatever Oil weight include a good contingent of Zinc (DiThioPhosPhate)

HD539 · May 10, 2021

I’ve been running this in both my Hemi car and my 383 car for a couple years now. No complaints.

Davison · May 11, 2021

68HemiCharger said:
I still don't have an owners manual for my recently acquired 1968 Charger 426 Hemi. Stock all original engine. What is the reccomended oil viscosity? I'm seeing many people saying 10-40, 15-40, 20-50. What does the manual say?

Yes I will be running a Zinc oil.

View attachment 1108453

I don't have a Hemi owners manual, but I do have a 1972 Plymouth Road Runner owners manual. For the 440 at 32+ degrees 10w-30, 10w-40, 20w-40, 20w-50, 30 are all acceptable. For maximum performance driving 20w-40, 20w-50, 30, 40 with Mopar High Performance Sulferized Ester #3683842. I use Valvoline VR-1 Racing 20w-50 conventional. The engine is original with low miles and not rebuilt. If it was rebuilt, I would use the same oil in synthetic, or what the rebuilder recommended if he had a specific choice. Both VR-1 oils have plenty of zinc and phosphorous for flat tappet engines.

RemCharger · May 11, 2021

Back in the day they rec'd straight 30. A lot of warranty engines back then lol

Dean Prevolos · May 12, 2021

My 67 Hemi Charger glove box manual, see photos attached, states the recommended oil at specific temps. Also the capacity is 5 qts.

5.7 hemi · May 12, 2021

Your bearing clearance’s should dictate what oil on the hot side you should run and the area of the country that you live in should dictate what you run on the cold side.

426 Hemi oil viscosity

68HemiCharger

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91r/t

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AR67GTX

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Runcharger

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Challenger340

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HD539

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Davison

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RemCharger

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Dean Prevolos

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5.7 hemi

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