oiling issues

[valiantrick]

hi guys. The previous owner on my valiant used "76" 20W-50 racing motoroil, and the pressure is steady just under 75 psi (hv-pump). But when i went to the local shop to buy oil, he said that 75 psi is way to much and that the timing chain would wear down and lose its tension wery quickly. he recomended a 10w-30 and the pressure should never be higher then 50 psi.
what is your opinion about this?

 

[66dartman]

This is just opinion, but it will take less horsepower to pump 10w-30 than 20w-50. Might be easier on the chain.

 

[dgc333]

The generally accepted rule of thumb is 10psi for every 1000 rpm. So if your car is a street car that sledom exceeds 5000 rpm then 50 psi is plenty. I would certainly give 10W-30 a try.

Some things to consider;

1. 80% of the wear in an engine occurs during start up. A thinner oil will get to the parts faster than a thicker oil so less wear.

2. Besides more load on the timing chain there will be more load on the oil pump and cam gear when running high pressures. The gears usually fail before the timing chain.

3. High volume oil pumps have the capacity to suck the oil pan dry faster than the oil can run back down resulting in lost pressure at high rpm's. That's why a HV pump is not normally recomended unless you are enlarging the oil pan capacity.

4. If you are using the factory gauge in the dash to judge your oil pressure then you really have no idea what the pressure is. The factory gauge is really only good to see a change, they are not at all accurate.

 

[valiantrick]

ok, thnks for the advice. Will try 10w-30. The oiling system is stock besides the hv-pump, windage tray and deep sump. It´s a street/strip, on the strip the revlimiter i set on 6900 rpm.