Hello,
First off I would like to thank all who contribute their valuable input - I recently found this forum, and it helped me solve a no heat/low temperature problem easily and cheap (heater core flush and thermostat change)!
I have a 97 Blazer LS4 door, with 110 000 KM's (70,000 Miles)
I have 2 questions:
First off, I have noticed my oil gauge/pressure drops toaline markbetween 0 and the midpoint, above the 1/4 mark, when I am at idle and the engine is fully warmed up. Once I start moving it will rise above the midpoint and stay there. Also, when the engine is warming up, it will stay well above the midpoint.
For reference, on the gauge, pressures in KPA are 275 for the midpoint, and 550 for the max (I think this is 40 PSI mid and 80 PSI max).
Is the fluctuation normal?

Second, Temperature.
Since the heater core flush and thermostat change, the temperature runs fine (about 70 C or 180 F), but when I come off the highway and come to a stop light, especially a long one (say a minute or so), the temp rises to about 90 C or 200F. Once I start moving again the temp drops and holds.

Is this normal?
Any help would be appreciated.
Thanks

 

The coolant temperature fluctuations are normal, but the oil pressure is not. A cold engine should have about 40-50 PSI of oil pressure and when warm shold be about 40 at idle and 60 above idle.

 

All of that sounds perfectly normal. Oil pressure will fluctuate depending on engine rpm. The old 'rule of thumb' is 10psi of pressure needed for each 1,000rpm. Chevy says the minimum pressure should be no less than 8psi at idle.
Temperature can rise slightly at long idles, plus a standard factory gauge is not all that precise.

 

Your oil pressure sounds perfectly normal. You should have an increase of 8-10psi for every 1000RPM the engine is turning.

Here are the specifications from GM:

 

Thank you very much, very helpful.

 

same issue,pressure seems good but the gauge is constantly fluctuating at idle between 1/4 to half way on the gauge. rises above when driving. some days it is steady and doesnt fluctuate at all. bad gauge or sending unit???

 

It is possible that the sending unit is faulty. You could see if it may be a wiring issue by moving the wiring at the sending unit around while someone watches the gauge.