Oil Issues?
07-11-2014, 12:47 PM
#1
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Oil Issues? Hello all,
I bought a 1997 Firebird Formula with the LT1 last April. It has 137,000 miles on it. After about one month I changed the oil and filter. Before changing them the oil pressure gauge always stayed pointing straight up, cold or hot, no matter what engine RPM. After changing oil the gauge sits straight up only when the engine is cold. After warmup it drops to 20 psi at idle but jumps up to 40 psi when above idle. The oil I used was Valvoline Synthetic 5W30 (if I remember correctly, or what is on the oil filler cap is what I used). The filter is shorter than the one I took off.
I wasn't too concerned until yesterday. I had met a friend for lunch, a 20 minute drive across town on a 95 degree plus day. After 30 minutes I left and pulled out on the road and stopped for a red light with the AC on. The engine started loping like it was running on 4 cylinders. I didn't look a the oil pressure though should have, I shifted into neutral and held the RPMs up close to 1400 and it ran smoothly. I think the oil was thin from the heat and the pressure was low enough the fuel pump was trying to cut off from low oil pressure.
Should I go back to regular oil, use a thicker oil, or has the shorter filter had an effect on oil pressure? Any ideas what's up with this?
I bought a 1997 Firebird Formula with the LT1 last April. It has 137,000 miles on it. After about one month I changed the oil and filter. Before changing them the oil pressure gauge always stayed pointing straight up, cold or hot, no matter what engine RPM. After changing oil the gauge sits straight up only when the engine is cold. After warmup it drops to 20 psi at idle but jumps up to 40 psi when above idle. The oil I used was Valvoline Synthetic 5W30 (if I remember correctly, or what is on the oil filler cap is what I used). The filter is shorter than the one I took off.
I wasn't too concerned until yesterday. I had met a friend for lunch, a 20 minute drive across town on a 95 degree plus day. After 30 minutes I left and pulled out on the road and stopped for a red light with the AC on. The engine started loping like it was running on 4 cylinders. I didn't look a the oil pressure though should have, I shifted into neutral and held the RPMs up close to 1400 and it ran smoothly. I think the oil was thin from the heat and the pressure was low enough the fuel pump was trying to cut off from low oil pressure.
Should I go back to regular oil, use a thicker oil, or has the shorter filter had an effect on oil pressure? Any ideas what's up with this?
07-11-2014, 01:43 PM
#2
Fuel pumps are electric.....low oil pressure or zero oil pressure wont affect their operation.
Also, if the oil pressure gauge was straight up no matter what rpm you were at.....it was not working. For some reason that oil change got your oil gauge working again. Maybe the oil pressure sending unit was all gummed up from the old oil.
Regular oil is better in my opinion, especially for an old engine.
Not sure why it started loping......oil really has nothing to do with the engine operation regarding spark plug firing or fuel delivery.....so that's pretty strange. probably not related to the oil change.
.
Also, if the oil pressure gauge was straight up no matter what rpm you were at.....it was not working. For some reason that oil change got your oil gauge working again. Maybe the oil pressure sending unit was all gummed up from the old oil.
Regular oil is better in my opinion, especially for an old engine.
Not sure why it started loping......oil really has nothing to do with the engine operation regarding spark plug firing or fuel delivery.....so that's pretty strange. probably not related to the oil change.
.
