What Oil Weight In A 8.1

[djv1951]

What oil weight are you using in the 8.1 engines. I know the owners manual states 5W30 or 10W30.

[dewfpo]

I'm using 5W40 synthetic.

 

DEWFPO

[sack1]

I'm using 5W40 synthetic.

 

DEWFPO

 

 

Did you notice anything after switching to 5W40? Less consumption, lower mpg for example?

[dewfpo]

I'm using 5W40 synthetic.

 

DEWFPO

 

 

Did you notice anything after switching to 5W40? Less consumption, lower mpg for example?

 

 

Much less oil consumption, no change in mpg's.

 

With the 5W30 oil in the crankcase I had a LOW OIL ALERT light come on after 5,300 miles on the oil. I'm not sure if that means I'm 2 quarts below full or what. Now, with the 5W40 in the crankcase I am 1/2 qt. down from full with 2,850 miles on the oil so that would be 1 qt. per 5,700 miles or so.

 

DEWFPO

[GMSatan]

My Dad's been using 10W-30 for about 5 years now. It does consume a bit, but nothing to be worried about.

[96chevy7.4L]

Seems that 10W-30 oil and a 180 degree thermostat cut oil consumption. My dad and a few guys I know say the same thing. Most I have talked to say the 180 degree thermostat alone helps quite a bit. Just my experience.

[ddbck]

5W30 Castrol in mine

[alaska511]

I'm using 5W40 synthetic.

 

DEWFPO

 

 

Did you notice anything after switching to 5W40? Less consumption, lower mpg for example?

 

 

 

That is what I switched to with my 8.1 as well. I was consuming a bit with 5w30. Never an issue with the 5w40 and no change in mileage.

[jro909]

run whats recommended in your owners manuel all 8.1s consume oil its how it is, for a motor of that caliber its a given

[yukon25008.1]

Im running 15 40 rotella t synthetic, and dont notice much oil loss at all, i also DONT have the 180 stat yet.

but i also heard the same thing that lower temp WILL reduce consumption of oil noticably.

 

your weight of oil i think also matters on the time of year -5 or 95 degrees outside

[Z45]

The only thing the 180° will do is open fully sooner, it will not change operating temp of the engine to 180°. If the cooling capacity of the engine is so that the engine gets to 210° with a 195 deg thermostat, it will still get to 210° with a 180 deg thermostat. All the stat does is control the lower operating range of the engine by staying closed to the pre-set temp.

 

The thermostat does not control the engine temp like like the HVAC in your house will keep it a 75°, as many seem to believe.