Best Oil for a Slant Six?

[RGC440]

Yardbird, I have not researched this, but I think the early /6 was during the time that it voided the warranty if you used multi grade oil.

 

[metalchewy]

ever since Valvoline VR1 came out I've been using their 10w40 in my old 273. It has a higher zinc content so I no longer deal with the additives on my oil changes for the flat tappet mechanical lifters.

Most of the standard dinosaur oil no longer has the zinc these cams and lifters need.

 

[Dusty]

My '82 Ram D150 with Slant Six engine needs an oil change. Though Dodge calls this version of the D150 the "Miser" I never skimp on the best multi-viscosity synth oil available.
But what viscosity makes most sense ? We have mild winters, never below zero, with summers rarely above 100.

Since I happen to have a Dodge truck service manual for that year:

LUBRICATION

For Service SE only

Ambient temp over 32F - SAE 30, 40, 10W-30, 10W-40, 10W -50, 20W-40, or 20W-50

+32F to +10F - SAE 10W-30, 10W-40, 10W-50, or 20W-20

+10F to -10F - SAE 10W, 10W-30, 10W-40, 10W-50, 5W-20, 5W-30, 5W-40

Below -10F - SAE 5W-20, 5W-30, or 5W-40

(They still make a 20W-20?)

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, 18” wheels. Build Date: 3 June 2018. Now at 132333 miles.

 

[metalchewy]

(They still make a 20W-20?)

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, 18” wheels. Build Date: 3 June 2018. Now at 132333 miles.

Isn't that just SAE 20 weight oil?

I haven't seen that for years.

 

[Dusty]

Isn't that just SAE 20 weight oil?

I haven't seen that for years.

Yeah, neither have I.

Since there's a winter blend "W" in the in the type, I suspect it is not straight 20 weight oil.

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, 18” wheels. Build Date: 3 June 2018. Now at 132333 miles.

 

[Marshall]

My take, any new oil, 10/30 usally is better then any old oil. In that motor, it will not really care if it's in good shape. if its blowing some smoke, then step up to next weight. You have to be careful of the tree huggers in BC,

 

[MrBonez]

My take, any new oil, 10/30 usally is better then any old oil. In that motor, it will not really care if it's in good shape. if its blowing some smoke, then step up to next weight. You have to be careful of the tree huggers in BC,

Been running 15w40 Delo with a 10% Lucas mix in my old S10's 4.3 for years and it's still running strong (300,000+ miles), gives a puff of smoke when it's started cold and maybe for 30 seconds afterwards if that long.
Really doesn't use oil between oil changes either.

I'd suggest about the same for your slant because those engines were spec'ed (Engineered) for oil of that weight range, usually 10w30 works fine in them but it has some miles by now so it's not a bad move to step up to the next oil weight range and keep driving.

 

[Marshall]

Up in this country , winter temps are usually freezing to -30 so 15/40 would be a bit heavy unless kept inside or block heater used.
Summer time it would be just fine.

Yrs ago I had a S10, great little truck running around the farm, forget what year, 4 sp, smaller motor, 2.8? maybe, fellow down the road wanted it , so I bought a 89 Dakota .

 

[MrBonez]

Up in this country , winter temps are usually freezing to -30 so 15/40 would be a bit heavy unless kept inside or block heater used.
Summer time it would be just fine.

Yrs ago I had a S10, great little truck running around the farm, forget what year, 4 sp, smaller motor, 2.8? maybe, fellow down the road wanted it , so I bought a 89 Dakota .

If it was a V6 then it was either a 2.8 or 4.3, 4 speed trucks were all 2.8's that I'm aware of.
Mine is a 4.3 with a 5 speed and it's a 4x4 truck too.

 

[SKYDOG 69]

Down here in central Fl with a 83 D150 Miser/slant 6. Man i'm just gonna stick with the old Lucas 10w30 Classic. Several option's i know, and all are purty good. Maybe i am going overboard with the old slant six.But i put in 5 qt's of the Lucas and 1 qt of the stabilizer. What the heck. Spoil the old gal.

 

[Hagar1]

I thought the Slant Six would run on rendered yak fat...

Probably would! The old "leaning tower of power" was one of the most reliable engines "out there" right up until they went with hydraulic lifters.

 

[pacofortacos]

I would run 10-30, that's all we ran back in the day. Maybe the 440 in my Cuda ran 10-40 but everything else was 10-30.

Modern oils and non-roller motors aren't a good mix, I would definitely add something or a special oil.
Maybe with the location of the cam and the low valve spring pressures on the 225 it might be ok on just a standard newer oil?

The old slant 6 was able to live on almost any oil and sometimes almost next to none hahaha.