L Series Oil Stick Calibration

[ryn004]

Solving a previous owner mystery and making sure my engine has the correct oil. So this is my situation:

 

• Engine: L20ET (throughout my build I learned the specs are the same as an L28), with OEM oil stick tube blocked
• Oil Pan: Center Pan with custom oil stick tube - my guess the engine block and pan were not originally fitted
• together.
• Car: 1976 Datsun 260z

 

Calibration steps (Could someone please confirm if I'm correct):

1. Empty all oil from drain plug and oil filter
2. Pour in 4 litres
3. turn over engine, let oil settle and Mark 'LOW' point
4. Pour in an addition 1 litre (5 litres in total)
5. Turn over engine, let oil settle and Mark 'HIGH' point

 

Note: I'll be re using the oil filter, it had oil but literally done 0 miles.

 

[DanielC]

I put 4 1/2 quarts in a L-20-B.  My experience with four cylinder L-engines is if the oil level is slightly too low, when the engine is cold, and cornering, the oil pressure will drop, because the oil pick up can draw in air. 

 

All your steps to "calibrate" the dipstick are pretty much meaningless in my opinion. 

The important factor is that the oil pick up does not get uncovered in operation of the engine, when accelerating, or slowing down, or cornering.  You want to maintain oil pressure when the car is running.   Most likely, the oil level will be the lowest when the engine is cool, or cold because the thicker oil takes longer to run back down into the oil pan.

 

You need a way to monitor oil pressure when the engine is running.  You car may have an oil pressure gauge, but you need a gauge that responds as fast as the tachometer does, because that is how fast the oil pressure changes with engine RPM.  If you want to know the oil pick up has sucked some air, you need a fast gauge response.  

Most oil pressure gauges are damped to NOT respond quickly, because too many people think oil pressure should remain constant, and a lower oil pressure at idle with a hot engine causes people to unnecessarily worry.

 

I would put 5 quarts in the car, with a new (Nissan) oil filter.  Start the car, and drive it, closely watching the oil pressure.  If the oil pressure drops when cornering, or accelerating, or braking, add a half quart more.    Drive the car again, and see if the oil pressure remains steady.  If it does, that is your low oil mark.

 

Too much oil will also cause air in the oil pump.  if the oil level is too high, the crankshaft will hit the oil, and whip air into the oil.  this air may also get to the oil pick up.

Edited October 17, 2018 by DanielC

[datzenmike]

That pan looks well baffled so hard cornering, acceleration and hard stopping shouldn't be a problem. Check how far down the crankshaft counterweights extend into the pan and make sure the oil level is well below that. The pick up must always remain submerged, the oil must be able to quickly drain back to the lowest point and the crank must not whip it into foam.

[Stoffregen Motorsports]

Calibration is a good idea. The best way would be to fill the oil pan with the required amount of oil while off the car and then take measurements. One measurement to make sure the oil pickup is adequately submerged, another measurement to set the mark on the dipstick.

 

If your block has the original location for the dipstick blocked, is it with a plug? or is it cast that way? If it's a plug, you can remove it and install the correct dipstick tube there. If it is cast without a hole, then drill a new hole and use that location for the dipstick tube. I've done this many times.

[datzenmike]

Engines tilt up at the front. So allow for this front tilt. I used 4 L of water, less messy.

[Stoffregen Motorsports]

Yes, water. Good point.

[datzenmike]

I knew you knew that.