Contour Enthusiasts Group Archives Forums Modifications Duratec Performance Oil Pan Article

It's been published like 50 million times!

3L heads have three drains. The 2.5L heads in the contours have two drains.

There is no rhyme or reason to the bearing failures, no definite pin on the oiling system. There is much less proof for the crank whip and harmonics issue.
Several theories loosely fit what is happening.
Most of us tend to go with oil starvation from a combination of sloshing at a time when there is a failure to drain back to the pan...RE: Right hand turns. There are no drainbacks in the 2.5L heads at the rear of the engine...or left side as you sit in the car.
The hard right turn theory is that there is a lot of oil in the heads under higher rpm loads. The hard right turn doesn't allow the oil to drain back to the pan and it pools in the top. The oil in the pan also sloshes and then the pickup sucks air.
The combination of events causes bearings to loose oil film protection.

The thinner oils are more susceptible to this. Running a slightly thicker oil isn't recommended for friction purposes, but it could save your motor since it has a higher viscosity and will take longer to bleed out of the rods.

Recommended oil weight is 5w-30 but I ran 10w-40 much of the time in my car AND 20w-50 in deep summer in Arizona. Oh, and I always ran 6 full quarts at oil/filter change time.
I've had DemonSVT get all over my case about bearing clearances and the like with the thicker oil, but I know what it is like in a hot climate and I have plenty of proven miles.
I ran the hell out of my engine on twisty mountain roads over souther arizona, many hard long turns going up the mountains.
The bottom line was at 40K miles when I converted to a 3L engine, those rod bearings looked like new, completely unmarked.
The 3L hybrid with 2.5L heads that I did back in 2001 NEVER had a problem and the bearings looked like brand new.
I always ran 10w-40 in it once I installed a turbo on the same motor...no issues.
This isn't the only answer, but I stand on my experience and tell you that oiling issues described here are probably the best guess that we have. Oh, and I have been completely through this powertrain 3 different times. I've had two 3 different 3L engine configurations to include the current oval port 3L setup, so that is where I am drawing my claims of experience.