[bzack]

"HP/HV oil pump and 20W-50 oil, is this builder stuck in the 80s? You'll be lucky if you don't collapse the oil filter element or blow the can off the block. That's a bad combination." - Tom Mobley


I run 20W50 in my 350 SBC with Big Block Oil Pump. Last engine had almost no oil pressure so when I built this one I went all out. It has great pressure, maybe too much but after my last engine I was happy to see so much pressure. However after reading the above today it got me thinking. Also I have quite the bad oil leak coming from the oil port at the back of the engine near the intake manifold. Just pours out like crazy but I just kinda ignored it all summer and kept toping it up. What you guys think? Should I switch to 10W30 and what can I do about the leak. Thanks.

[Ricks69]

Hi,
There's a good article in last months Car Craft about high pressure vs high volume and differing viscosities of oil. If your going to run a higher wieght oil it definately needs to be synthetic. They got the most HP with 5w20 synthetic oil, although we are only talking a few horsepower. You can read the article here http://www.carcraft.com/techarticles...mps/index.html
As to the oil leak in that location it's either the oil pressure sending unit leaking from it's hole or there is a plug half way under the back of the cylinder head. If it's the one under the cylinder head, the head has to come off.
Rick

[bzack]

Good article. The pump I use is the Big Block one in their test. Seems like they recommend 5W20 Synthetic. What do other people use on a low km performance street motor? The other reason I went with the big block pump was because it oils my two turbos as well. Oh I also have a comp cams solid flat tappet cam if that makes any difference. Currently I just use non-synth 20W50.

[71-454]

Current technology indicates that FLOW is the key component to lubrication given todays oils, NOT viscosity. Therefore, I wouldn't plan or running 20W50 unless you were planning a couple warm up laps at 110mph right before the green flag....

[Tom Mobley]

bzack,

your car with turbos, if you run it hard at all I''d think seriously about running synthetics. Oil is exposed to much higher temps in a turbo than it would ever see in a N/A engine. Personally, I don't recommend synth oils unless there's an actual need, but IMO this qualifies.

You've heard all the usual lectures about letting the engine idle awhile after running the turbos hard and all that jazz, I expect?

[bzack]

Yea I usually try and drive around a bit slowly to cool them down and let it idle for a while. Anyways sounds like a lighter weight synthetic would be best for my engine but I'm just worried about having the flat tappet cam. I broke it in with lucas zinc break-in and I've been driving the car for over 1000 miles with no issues. I'd hate to change oils and toast the cam. I don't know if a synthetic 5W20 or 5W30 would be worse on the flat tappet than the non-synth 20W50 I'm using. So if anyone could shed light on this last thing that would be great. Thanks.