Oil Pressure

[Sargeant_Khan]

Hi guys, just a quick query. My oil pressure seems higher than normal, not knowing what normal is I need to ask. But the rocker is so tight and it still isnt containing the amount of oil pressure and neither is the oil filler cap. I'd like to add my oil pressure idles on about 30 psi and when driving it sits at around 40-50, when you punch it, it winds right around to 80-90.
Im just using a regular fully synthetic oil for "turbo cars" recommended by a forum member. Also, The car feels like it has lost a bit of power and it surges at top end. I just found that the wastegate to the exhaust pipe bolts have come off soooo maybe thats my power problem or is this oil pressure choking my turbo? Cars not smoking ummm oil is coming out the sump gasket a little bit...pickup blocked maybe? yeah I dont know what else to say, each piston is reading 170 on the compression gauge aswell.

Any help would be great as always guys.

:beer

[Lummy]

Your oil pressure isn't a problem at all. Mitsubishi engines are notorious for high oil pressure and your readings aren't at the high-end of the scale at all.

For comparison, my engine at idle runs about 60 psi and under full load increases to between 110 and 120 psi. It worried me at first, but I've been assured by many that it's common in these Mitsubishi motors.

The general rule for engines is around 10psi per 1000rpm - that's what's considered as the minimum necessary to look after your engine.

[TOMSUN]

is that a for a 10-40w oil?

[Lummy]

Are you asking about the general rule or about my oil pressure?

The general rule is very general, just a basic guide as to what to expect for oil pressure.

As for my motor, yes, I use Motul 4100, 10w-40 oil.

[Sargeant_Khan]

Im using a 5w 40. Thanks for the replies guys. Its a relief that my oil pressure is normal. So why is it blasting out my oil filler cap and my rocker gasket. Could there be a problem with the breather hose being blocked maybe? My gauge only go's up to 100 psi on oil pressure thats why I was concerned, must be a na thing.

Cheers :beer

[Lummy]

I don't know the finer details of your engine, but the oil sounds too thin to me.

Don't take my word for it though, I'm no expert in this field - perhaps someone else can give their opinion?

[Sargeant_Khan]

ahh, that could be why its squeezing passed my seals. I wonder. Im going to use my thundercats badge to call redzone to this thread!

[enthuzed]

Not that I'm an expert but with your TC I'd be running a multivalve oil, something like a 10w40. A SOHC Staz would run a 20w50, so 10w40 is going to look after the top end. Anything thinner is just too thin.

[Sargeant_Khan]

thanks, I will change the oil tomorrow and let you know.

[thrash]

wow.. i thought the thinner the better.. and that thicker oils were only run after an engine got to a certain age and the rings were no longer sealing all that well?

[enthuzed]

You're right thrash for one fundamental reason: If the oil is too thin at normal operating temperature it will not be capable of staying on the pistons and cylinder walls and will wash right past, even with rings, pistons, bores being in perfect condition...meaning they're not getting much lubrication. This is where most friction in an engine occurs and so will cause premature wear, plus then there's excessive heat build up which just compounds the wearing issue.

Once again thrash you're right, this also holds true for that tired engine, a thicker oil is used as it's less able to be washed past the rings.

For starting, you still want low viscous oil because this is where most engine wear occurs, so 5w or 10wSomething is good. But 5w might be a bit thin for the seals as mentioned.

Best thing to do is get advice from your engine builder. As an example, if you've got forged pistons, or gapless rings, or other special stuff you'll want to use product that keeps your engine warranty valid.

If you want a special oil, buy Martini Racing's 10w60, it'll handle the cold starts plus will be in good shape after massive punishment around a racetrack. Don't expect this stuff to be cheap though:
www.martiniracing.com.au. Aussie products too!

As Castrol used to say in their advertising, oils aint oils.

[OLD FART]

Hey guys remember oil preasure is resistance to flow IE tight clearances = high preasure worn motor = lower preasure You can have to much preasure
Oil numbers 5W40 the 5 is the viscosity when it is cold so it will lubricate the motor faster from a cold start than say a 20w40 BUT BOTH will give the same reading when hot. To put it simply multi grade oils say a 5W40 behave like a single grade 5 weight oil when cold and the same as a straight 40 grade when hot so you get better wear protection in other words it is thin cold and thickens up as it gets hotter

[thrash]

but then.. that would mean running something like 0W40 would be ideal right? Since most of the damage happens on start up, the 0W-ness of the oil will move through the motor quicker and cleaner while cold, and you'll still get decent protection from the 40W at running temp?

[enthuzed]

As Srgnt Khan is finding, the 5 weight oil is too thin, it sounds like it's getting past the seals, so less than that isnt going to help.

And you do need a certain amount of resistance, especially when the engine is cold. When you start your car you'll find the oil pressure at idle is initially quite high. You want that.

The zero and 5 weight might be useful in countries like England where it's much colder.

Calling the Maroochydore Maestro, wonder what he'd say...
I wouldn't imagine less than 10 weight...where are you Dave?

[thrash]

As Srgnt Khan is finding, the 5 weight oil is too thin, it sounds like it's getting past the seals, so less than that isnt going to help.

this is assuming the thinness of the oil is the actual problem he is having..