406 oil recommendation
Thread Starter
Instructor
Joined: Mar 2005
Posts: 129
Likes: 0
From: Layton ut
406 oil recommendation
Just wondering what viscosity of oil to put in my fresh 406. I plan to spin it to about 6200 RPM. I just had the crank ground and installed new bearings. The front 4 main journals mic'd out at about 0.0020-0.0025" clearance and the large rear journal has about 0.0033". Rod bearings are at about 0.002".
I'm breaking the engine in right now. I haven't revved it above 4000 yet. With the engine running on 10w30 conventional oil cold (150 degrees or less on my oil temp gauge) it has about 65 PSI at 900 RPM and almost 80 at 2000 rpm up. At 200 degrees it drops to 45 psi at 900 rpm and 65-75 above 2000. The lowest I can get it to at idle is 30 with the engine oil at 250 degrees.
The 406 has the larger bearing diameter compared to the 350s. I'm worried about high rpm use and not getting enough oil through the bearings. The machine shop said to run 50W racing oil in it. I'm thinking more like 0w20 because the pressure seems kinda high.
Any thoughts? I have a standard stock oil pump, too.
I'm breaking the engine in right now. I haven't revved it above 4000 yet. With the engine running on 10w30 conventional oil cold (150 degrees or less on my oil temp gauge) it has about 65 PSI at 900 RPM and almost 80 at 2000 rpm up. At 200 degrees it drops to 45 psi at 900 rpm and 65-75 above 2000. The lowest I can get it to at idle is 30 with the engine oil at 250 degrees.
The 406 has the larger bearing diameter compared to the 350s. I'm worried about high rpm use and not getting enough oil through the bearings. The machine shop said to run 50W racing oil in it. I'm thinking more like 0w20 because the pressure seems kinda high.
Any thoughts? I have a standard stock oil pump, too.
Burning Brakes
Joined: Feb 2002
Posts: 804
Likes: 5
From: Fresno CA
I would stick to a conventional 10W-30 for the first couple thousand miles until the rings are good and seated and everything is broken-in, then you could switch to a 10W-30 synthetic if you like (that's what I'm doing with mine). You have tight clearances, and I'm sure no really high valve spring pressure, and you are really not spinning the engine that high, so I don't see the need for a higher viscosity oil and certainly not 50W.
Racer
Joined: Jul 2010
Posts: 308
Likes: 2
From: Kansas City MO
What cam is in it? (roller or flat tappet?) Also - how do you intend to use it (drag race, street, road course, etc.)
For a roller cammed engine on the street primarily (and an easy to find oil) - I'd run a Mobil-1 5W30 or 10W30 just keep an eye on the hot idle pressures - I'm guessing you've got a HV pump in there that's why the pressures are so high...
Flat tappet - just have to find a good oil with ZDDP in your area (Brad Penn, Valvoline racing, Castrol HD 30, etc.) - most new formulation diesel oils are reducing the Zinc (because of the converters and DPF's on the new diesels... same reason the gas oils had to go away from zinc...)
For a roller cammed engine on the street primarily (and an easy to find oil) - I'd run a Mobil-1 5W30 or 10W30 just keep an eye on the hot idle pressures - I'm guessing you've got a HV pump in there that's why the pressures are so high...
Flat tappet - just have to find a good oil with ZDDP in your area (Brad Penn, Valvoline racing, Castrol HD 30, etc.) - most new formulation diesel oils are reducing the Zinc (because of the converters and DPF's on the new diesels... same reason the gas oils had to go away from zinc...)
Le Mans Master
Joined: Jun 2006
Posts: 5,642
Likes: 5
From: One day you're a Comet...the next day you're dust... Arkansas
Get on synthetic after break in, 5w-40 Rotella T. Do NOT go to heavy oil. It's the additives and type of oil that is more important than focusing just on weight (viscosity rating), You want to protect and flow quickly at all temps.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
I would stick to a conventional 10W-30 for the first couple thousand miles until the rings are good and seated and everything is broken-in, then you could switch to a 10W-30 synthetic if you like (that's what I'm doing with mine). You have tight clearances, and I'm sure no really high valve spring pressure, and you are really not spinning the engine that high, so I don't see the need for a higher viscosity oil and certainly not 50W.
Jake
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