Backdraft book says use 20w50 oil

[bobcowan]

Depends on the engine installed. If the engine is built with loose tolerances in the bearings, you'll need the higher hot viscosity to maintain pressure.

But, you're right, 20W is pretty high for a new England winter. Red Line sells a 10-W50 oil. It's expensive, but could be just what you need.

[Bxx1]

Mobil 1™ 0W‐40 contains: Phos: 1000 PPM Zinc: 1100 PPM
Sufficient Zinc and Phos for roller lifters. I would not recommend for flat tappets due to the need for higher Zinc and Phos requirements for those engines.

OW for those cold early morning start-ups.
"Has excellent low temperature capabilities for rapid engine protection at start-up" from Mobil

"High performance engines Most operating conditions, from mild to extreme"
From Mobil.

Happy motoring.

[genolan]

BXX1 this makes sense can anyone give me a reason not to switch to Mobile 1 0w 40 from Castrol 20w 50. I have roller rockers but have no idea on bearing clearance. I took the car for a hard run last night and noted the pressure at idle 900rpm before (65PSI) and after (25psi)

[Slick61]

my engine builder (Keith Craft) recommended 20W-50... it's all I've ever used.

[bobcowan]

Originally Posted by genolan

BXX1 this makes sense can anyone give me a reason not to switch to Mobile 1 0w 40 from Castrol 20w 50. I have roller rockers but have no idea on bearing clearance. I took the car for a hard run last night and noted the pressure at idle 900rpm before (65PSI) and after (25psi)

No reason not to try a 0W-40 oil, and see what your hot pressures are. If they're too low, then go back to the "thicker" oil.

I'm not a huge fan of Mobile 1. It's not bad oil for most vehicles. It's not a true synthetic oil, but it's priced like one. IMO, that makes it a bad value.

Even in New England, a 10W-40 would not be a bad choice. 10W is rated down to -20*. So unless you're driving at temps lower than that, there's no need for a lower viscosity.

If you want a wide spread like 0W-40, you'll need to switch to a semi-synthetic like M1 or Syntech, or one of the 4 true synthetic oils.