[rlb3]

My 350 knocks right when I start it but then quits after maybe 1sec. I have ben running 20w50 in it. My oil presure is 45psi when it is a cold start but once it warms up it idles at about 15 psi, when I put it in gear it drops to the line right before the red on the gauge(about 10 psi) so I want to know if I can use 10w60 synthetic oil in it to raise my oil presure a lil bit, because it seems very low to me. It has a new highvolume oil pump on it.

If I understand the oil numbers right 10w60 would be like straight 10 weight oil when it is cold but would be like straight 60 weight when warmed up.

Any help would be great

[S10 Racer]

Originally Posted by rlb3

My 350 knocks right when I start it but then quits after maybe 1sec. I have ben running 20w50 in it. My oil presure is 45psi when it is a cold start but once it warms up it idles at about 15 psi, when I put it in gear it drops to the line right before the red on the gauge(about 10 psi) so I want to know if I can use 10w60 synthetic oil in it to raise my oil presure a lil bit, because it seems very low to me. It has a new highvolume oil pump on it.

If I understand the oil numbers right 10w60 would be like straight 10 weight oil when it is cold but would be like straight 60 weight when warmed up.

Any help would be great

Even 10psi pressure at idle is "ok". I don't think changing to a different weight will help you that much. With the heavy oil you are running now would concern me on cold days. You might actually try a thinner oil such as 10W-30. The thinner oil will get through the motor quicker than the syrup you're using now. It sounds like you have main bearing issues if it knocks when started then quiets downs.

[hpete]

new rods and mains would help more than heavy oil

[eloc431962]

Originally Posted by S10 Racer

Even 10psi pressure at idle is "ok". I don't think changing to a different weight will help you that much. With the heavy oil you are running now would concern me on cold days. You might actually try a thinner oil such as 10W-30. The thinner oil will get through the motor quicker than the syrup you're using now. It sounds like you have main bearing issues if it knocks when started then quiets downs.

Couldn't it also be a weak oil-pump taking some time to pick up the oil ?



Cole

[Bonneville462]

Just because the oil pressure reading is high doesn't mean it's flowing.. Flow is what protects, not pressure..

Put some 10-30 in there without any additives...

The bigger the spread in numbers, 10-60 vs 10-30, means there is more additives in the base 10 grade oil... Synthetic is the oppisite, if you want to waste your money on synthetics that is....

[killerformula]

I agree with the above, 20-50 is pushing it now. The pressure is just an indication of the bearings in the motor. Oil is still making it through the motor, it just has less resistance. Adding more resistance artificially isn't going to help things.

Incidentally, I've seen motors run with almost 0 oil pressure warmed up at idle and very little cruising for years. Seen a main knock go for 100,000 miles. Keep the motor full of oil, go find yourself a core to rebuild in your spare time. Some time when you have a free 3 day weekend, make the swap and call it done.

K

[eloc431962]

Just be sure to replace the oil-pump when you do the bearings it is a must when doing the bottom end rebuild. and have the crank checked also IMHO



Cole

[S10 Racer]

Originally Posted by eloc431962

Couldn't it also be a weak oil-pump taking some time to pick up the oil ?



Cole

I never thought about that because he said it has a new HV oil pump in it and he didn't say anything about not having oil pressure on startup, only when warm. The pump could have excessive clearance causing it to lose some pressure but my money's on bearings and running too thick of oil.

Good seeing you Cole. Take care.