Synthetic oil in 1984 Corvette

[Walter F.]

When I purschased my 1984 Corvette I was told by the previous owner to use synthetic oil . He had the car for sometime and had put most of the miles on it before I purschased it. In th 9 years I have owned the car with 151,000 miles on it i always noticed low oil pressure at idle. The gauage us accurate as I had the dash rebuilt and was told the gauge was correct by the rebuilder.It goes down when warm to about 13 pounds. The motor is quiet, the lifters silent and I need to add a quart oil oil about ever 1,000 miles. I am just wondering does using synthetic cause low oil pressure?

[Edward J.]

Re: Synthetic oil in 1984 Corvette

Walter, syth. oil will not cause low oil pressure. I would run a test on the engine warm with a external gauge attached at the sender to check the psi, Maybe the sender could be a issue. Or just a well worn engine, worn engine bearing clearances tend to lower the oil pressures. at the point of what your reading on the Dash , the engine may run fine But would not push it to hard when the pressure is that low when warm.Gm engines with oil light instead of a gauge will turn the light on if pressure drops below 7/8 PSI. so you see your not far off. My advice is drive for now and keep a close eye on the pressure.

[Joe L.]

Re: Synthetic oil in 1984 Corvette

When I purschased my 1984 Corvette I was told by the previous owner to use synthetic oil . He had the car for sometime and had put most of the miles on it before I purschased it. In th 9 years I have owned the car with 151,000 miles on it i always noticed low oil pressure at idle. The gauage us accurate as I had the dash rebuilt and was told the gauge was correct by the rebuilder.It goes down when warm to about 13 pounds. The motor is quiet, the lifters silent and I need to add a quart oil oil about ever 1,000 miles. I am just wondering does using synthetic cause low oil pressure?

Walter------


If you're talking about 13 PSI at warmed-up IDLE, I'd say that's about right. Maybe a few pounds low but at 151,000 miles the engine does have a little wear on it.

Synthetic oil does not cause low oil pressure.

[Jim T.]

Re: Synthetic oil in 1984 Corvette

Walter the 13 PSI warmed-up at IDLE, is that pressure not using air conditioning and your 1984 in DRIVE? Reason I ask, my 1985 has lower oil pressure in this situation sitting at a stop light, the RPM if I remember correctly is less than 500. Pressure picks up leaving the stop light with the higher RPMs. Have 108,885 miles on it. I don't use synthetic oil in it.

[Duke W.]

Re: Synthetic oil in 1984 Corvette

When I purschased my 1984 Corvette I was told by the previous owner to use synthetic oil .

So what! What does he know? What does the owner's manual say about what oil to use and normal oil pressure? You should also find information in the AMA specs.

GM does not usually specify idle oil pressure range. Oil pressure is usually specified as a range on a hot engine at 2000 RPM and above.

Idle oil pressure does not need to be high because there is very little load on the bearings. Bearing load increases with the square of engine speed so bearing load at 5000 is one hundred times higher than at 500.

Most engines would have no problem with idle oil pressure in the 5-10 psi range.

Duke

[Walter F.]

Re: Synthetic oil in 1984 Corvette

Yes that is in drive with no Ac and the pressure does pick up when your RPMs are climbing.

[Walter F.]

Re: Synthetic oil in 1984 Corvette

I believe the last owner was under the assumption synthetic oil can prolong engine life and can be driven for longer periods of time without oil changes. I know my new leased Malibu requirs oil changes at 7500 miles. I was told not to bring the car back for oil changes until that mileage since it has a synthetic blend of oil. Its their car and they don't seemed worried about me using it that long times between oil changes. Reguardless I change my Corvettes oil with Mobil 1 every 2,000 miles.