Watch your oil pressure gauge during startup next time you change your oil and let us know what you see..

 

What will I see? Is it actually a prolonged period of no oil pressure or a short period before the guage reads the pressure that's there almost instantly? I may pull a fuse/relay on my LS3 because the tune/cam has it running faster than idle for an instant before settling down on start up. No way would I take the time/effort to do that on an engine that starts up at an idle. I've been maintaining literally hundreds of engines from tiny to 2500+ cid for years. Can't remember an oil related failure. Also, can't remember any manaul in 40+ years that recommends going to that extent on an oil change.

If you choose to, I applaud you. Attaboys and I'm sure you take excellent care of all your stuff. I'd rather use the time to do something else.

 

I think you missed my first post where I pointed out that every modern OBD-2 vehicle will crank over without starting if you hold the gas to the floor when you crank it over
I haven't watched the pressure gauge on my C6 but my previous vehicle showed zero oil pressure for 2-3 seconds after starting post an oil change, and this was from an analogue gauge that read instantly. For me that's 2-3seconds too much, but of course you can do with your vehicle as you wish...

 

Are you freaking kidding me. #1 the bearings don't lose the oil between them and the crank, rod or cam journals on an oil change. You probably do more damage letting the engine crank under compression without starting up even after an oil change than you would by just starting it. Just because it doesn't show on the gauge it doesn't mean the oil isn't there. The oil pressure sending unit is at the top of the motor, I guess oil pressure wouldn't be instant. #2 on a new engine build the bearings have assembly lube to lubrictate them during start up. You could probably run the motor for 10 minutes without oil pressure if something went wrong. It's more important to crank a new motor just to make sure nothing binds up that shouldn't. Lets get real here.

Just start the motor it's the best thing for it.

Ed

 

Why not install a preluber?

 

What is the reasoning behind that, if any?

Breaking news; oil is incompressible The oil pressure gauge detects the presence of oil pressure, not wether oil is there or not. If your engine is full of oil, oil pressure will show up on the gauge as soon as the oil pump gets up to speed.

You might want to read up a bit on engine building before you "get real". Getting real usually requires real facts . Starting a new motor is a lot more critical than just finding out if something binds or not.
Look, I didn't tell you what to do with your car or said your engine will be ruined if you don't do this; I simply explained what I observed on an actual car with an actual analogue pressure gauge and said what my reasoning was for cranking my car over a few times before I start it after an oil change. You get real.

 

Cranking the engine actually probably won't hurt anything, but it's not helping anything either. Your best bet is to get the motor up to idle speed, which it obviously isn't at when cranking and let the oil get where it needs to go by building some real oil pressure. There is no sense cranking the motor longer than needed at cranking rpm. If the bearings had a thin cushion of oil still on them you surely wiped that away while building minimum oil pressure with the slow turning of the pump during cranking

There has to be oil at the sending unit for the gauge to show any oil pressure. It would stand to reason that there is oil through the crank and up to the cam before the sending unit ever sees a drop. Maybe I'm wrong though and your motor works differently than everybody elses.

When starting a new motor the most critical thing is to make sure something doesn't bind. You're right in there being other critical steps to take, but mechanical failure is for sure the most important. Oil pressure is an after thought if something isn't right mechanically. I thought you'd know this being a mechanical engineer.

You're right, do what you want with your own motor. Just don't advise people to do somethings so fullish with theirs.

 

A engine can have oil flow without oil pressure. Harleys are... or were the same way. The oil pumps were set for flowing oil, not pressurizing the system. Moco issued statements all the time as people constantly tried fixing something that wasn't broke. On my 50 Pan, the oil light would come on all the time at idle, yet plenty of oil was flowing. Not saying the vette has the same characteristic, but don't lump flow and pressure into one thought. They are distinct and different entities.

John

 

Harleys don't have hydrodynamic (plain) bearings- they use roller bearings, thus no need for much oil pressure.
The reasoning for cranking without starting is that the loads on the bearings, especially the rod bearings, is much lower during cranking than when the cylinders are firing.
When I was racing Formula Ford and Formula Vee I always cranked up oil pressure at the start of each day. I never suffered a bearing failure in over 100 race weekends.
But I don't do it in a street car, even if it sets for several weeks, and I haven't had a bearing failure in 45 years there, either.

 

Will the un-burned gas left in the cyl flush the oil off the rings?? and might this be bad for the rings and cyl wall's?? and the gas ends up in the oil pan diluting the oil??
Maybe Spinmonster can chime in.

 

I'm not the Monster, but it starting without preoiling after and oil change is an issue for you, pull the fuses for the injectors and you can crank away - no worries about fuel washing either

Personally, I think it this were an important issue, the engineers at GM (as well as the bean counters) would have developed a procedure for this and a cautionary statement in the owners manual and service manual.

 

Lol, some of you guys crack me up. I always spin up a fresh motor with the injector and fuel pump relays and fuses pulled. After an oil change? No. There is still going to be enough film in there to cover it until it build pressure in the 6 seconds. Reminds me of those people who eat lettuce and bean sprouts, run 15 miles a day, wear sunscreen and won't go outside in the rain and die of a heart attack at 40. But, I do appauld your efforts!

 

 

The whole principle behind cranking an engine without starting is that it doesn't start because there is no gas being injected into the combustion chamber... So diluting the oil is not an issue.

 

If you pull the fuses to the fuel pumps, you're correct. If you use the "clear flood" algorithm in the ECM by holding the gas pedal to the floor while cranking, fuel is still being injected but the injector pulse width is decreased to achieve ~20:1 A/F ratio which is insufficient to sustain combustion. But the wide open throttle admits enough air to clear the excess fuel from the cylinders until the proper ratio is attained in the cylinder and the engine starts. If a flooding condition doesn't exist and you're using this "trick" to crank the engine without it running, fuel is being injected into the cylinder but no excess fuel will accumulate to worry about oil dilution.
I've only seen one time where the "clear flood" mode was used to clear a flood...actually it was used more to prevent a flood. A forum member had his engine coolant sensor go bad on his ZR-1 and it failed to the low temperature side. When he tried to start it, the ECM commanded max enrichment for cold start which is ~1.5:1 A/F ratio and it would belch black smoke when started. It eventually got to the point where it wouldn't start and I talked him through the "clear flood" mode on my cell phone and listened to it roar to life immediately. He was 1,000 miles from home and still had 3 weeks left on his trip (which is why he was in panic mode), his new "starting procedure" got him home so he could get it fixed and he was one happy camper.

 

A lot of worry about nothing.