oil help
 

I have been using 25/40 merc oil in my new 6.2s. motors run at about 175 degrees 40-50 psi after running awile say 4000rpm to 4500 then then bring down to a idle my oil psi drops a lot 20 as low 10 psi. I keep the engines up a little above idle so the oil psi is up say 20 but if broght to a idle its to low for my liking. why does the oil or engines drop so much in pressure ?? can someone give me any feed back thanks !!

Oil pressure is not as much of a concern as you think. You should be more concerned with oil volume. Think of a garden hose running without your thumb over the end of it. Water flows with a high volume out of it. If you were to put your thumb over the end of it, it creates more pressure but less volume. That is where synthetics come into play, they flow better at high pressure therefore creating better volume also.

Ok, but it still does not explain why the oil pressure drops like he described. Is this normal after running for a period of time at higher rpm's??

When the oil gets hot it thins out , less pressure. Once the oil cools down the pressure will go up. :ernaehrung004:

Our hp500 do the same thing but they do have 700hr on them, And yes they are ready to be gone through this winter.:drink:

Running for a while at 4000-4500 will cause the pressure to drop. Hotter oil=thinner oil. If it was too low, the alarm would sound. 10psi for every 1000 rpms is fine. If you want, try running some Mobil 1 15-50 wt synthetic.

Is this common for mx 6.2s do this with the psi, but what about the oil thickness is 25/40 merc oil enough protection.

This is normal for every engine to loss some pressure when it is hot . :boat:

is it normal to be at 10psi for new engines then as the oil cools it returns to 40 psi. I was thinking about calling merc to find out.

You need to find out how hot your oil is. You may have insuffecient cooling or a partial clog. Synthetics will hold up to the higher heat and keep the pressure and viscosity (resistance to flow) up.

If you have an infared thermometer hit the oil filter or any where before the cooler and check the temp.

If you do not have one than get some of these stick on thermometers. I use these all the time at work and are accurate and inexpensive. (cheap gauge) stick on your oil filter.

http://www.mv.com/ipusers/paperthermometer/ Industrial Application

The TL8-170 is what you would need. I also recommend these to anyone who does not have an oil temperature gauge.

some lucas oil treatment would help

Another problem is only 4.5 quarts in the 6.2's.

thanks everyone for your input.

My 350 mags do the same. 40-60 under load running. After a wot blast can drop to 10-15 @ idle. As oil cools idleing around , comes back up @ idle. Seemed to be worse during initial 20-40 hours and does not do it as much now that the "break in" is done. Running merc oil for warranty sake. No oil coolers on my setup either. That may be a something to consider.

If you purchase a quality oil, you don't need an oil treatment.

Ken

Lucas is a good product but probably not your answer.

In general what causes low oil pressure??...assuming your sending unit is working..gauge is working... oil pump and system is in good repair etc....

a. The high viscosity of the engine oil did not allow oil pressure to build quickly, and may also have caused the system to go into bypass, thus the low oil pressure. Going to Merc Semi Syn and Merc oil filter ought rule this out.

b. Possible engine damage may include; scored engine oil pump - damaged lead/tin overlay of crankshaft bearings (mains and rods) - damage to camshaft bearings - damage to lifters - damaged small end bearings of connecting rods - damage to bearings of engine timing/idler/accessory drive gear train.

Hopefully it's under warranty...

Yes .. I have a 5 year warranty , i'm going look into Semi syn oil too, again thanks :drink:

You may as well stick with conventional oil and save your money. If you don't want a 100% or Full synthetic, then you are wasting your money. Oils are not regulated like they should be, meaning a semi synthetic can basically have 1% synthetic properties to it, and they can call it a semi synthetic, and sell it to you for twice the cost. Additives, as far as I'm concerned, should never be used. If they were supposed to be in there, then they would be. An aftermarket additive can actually have adverse effects on oils, because they are properly made for all different oils, therefore can cause premature breakdown, because the two products in the crankcase can actually work against each other.