Proper Oil Pressure

[Richie G]

I just changed my oil and filter for the first time (71 240z) and was wondering if my pressure readings seem accurate to folks.  10w30 at idle (9000 - 9500) with the engine temp at midpoint gets me about 1/4 reading on the dial.  If I give it some throttle to keep it steady at 2K it climbs to 1/2 gauge and hold steady.  Does this sound right?  It seems the PO put on a new sending unit but it's the gold one which after some digging here it seems some people don't speak highly of.

Also I did some reading on dipstick type and accuracy and it seems my e3001 has just slightly shorter dimensions from shoulder to tip than most folks report.  My reading is about 3/16th over the fill line to the H symbol.  If I account for the shorter stick length it still puts me about 1/8 over what should be the fil line.  this was measured at cold engine after running it to idle temp and letting it cool down.  New filter and 10w30.  I know its best to have less oil than more but so far not a drip and it's been 9 hrs.

Edited July 1, 2023 by Richie G
forgot year and model

[psdenno]

15 hours ago, Richie G said:

I just changed my oil and filter for the first time (71 240z) and was wondering if my pressure readings seem accurate to folks.  10w30 at idle (9000 - 9500) with the engine temp at midpoint gets me about 1/4 reading on the dial.  If I give it some throttle to keep it steady at 2K it climbs to 1/2 gauge and hold steady.  Does this sound right? 

I've had my '71 since it was new and the oil pressure gauge has always read significantly lower than where I thought it should be.  You'll find that mentioned in many other threads on the web.  Google "1971 Datsun 240Z low oil pressure".  

[Racer X]

16 hours ago, Richie G said:

I just changed my oil and filter for the first time (71 240z) and was wondering if my pressure readings seem accurate to folks.  10w30 at idle (9000 - 9500) with the engine temp at midpoint gets me about 1/4 reading on the dial.  If I give it some throttle to keep it steady at 2K it climbs to 1/2 gauge and hold steady.  Does this sound right?  It seems the PO put on a new sending unit but it's the gold one which after some digging here it seems some people don't speak highly of.

Also I did some reading on dipstick type and accuracy and it seems my e3001 has just slightly shorter dimensions from shoulder to tip than most folks report.  My reading is about 3/16th over the fill line to the H symbol.  If I account for the shorter stick length it still puts me about 1/8 over what should be the fil line.  this was measured at cold engine after running it to idle temp and letting it cool down.  New filter and 10w30.  I know its best to have less oil than more but so far not a drip and it's been 9 hrs.

Regarding the oil level on the dipstick, I believe the sump capacity is 5 quarts. After changing oil and refilling, run the engine (so the filter is filled) and shut the engine off. After about 10 minutes check the level.

That should give an accurate reading, and if it doesn’t match the dipstick, then make a note of where the level is in relation to the original marks.

Now on to the oil pressure.

The rule of thumb, for any engine, is 10 psi for every 1,000 rpm of engine speed. So at 5,000 rpm, it should have 50 psi. The stock gauge is not an accurate gauge. You can use a good quality mechanical gauge, for peace of mind, to compare to the stock gauge. 
 

Also note that cold the pressures will be different than when the engine is at operating temperature, and will fall off some. Nothing to be concerned about, provided the 10 psi/1,000 rpm rule is met.

Being in California, you might also find that 20-50wt will give better oil pressure in the summer.

Edited July 1, 2023 by Racer X