Mahle oil filter symptons??

[Kokkolanpoika]

Hi.

I send this same message to V8forum.co.uk
And i like to hear more opinions because this is very hard to resolve.. I made same question our local Finnish american car forum, but 0 response.

I have got ~400hp tuned rover race/street V8 engine. 5.2litre engine..
I always use Valvoline VR1 20w50 mineral oil.
I usually use Fram, Coopers etc oil filters. But I know order those Mahle OC261 oil filters from another sublier.

First problem i have in summer 2011, i´ll lose some oil pressure on start up and then in hevy driving oil light start to "flick"
All this hapends after 800km distance in new oil/mahle filter..
I first wonder what it could be, then i change new oils in it + Hengst oil filter.. I drive last season without proplem approx 2000km.

Similar problem with this 2012 season.. I change new oils and New mahle filter again, i drived 680km and again oil pressure light start to flick in heavy driving after engine is becoming idle speed but car speed is +100km/h Also oil pressure is heavy low.
So i fit new Mahle oil filter again couple of days ago, and made test drive when engine is warm, no problem. But when engine is half way of warm and i made approx halt throttle burn out, oil light is flicking when engine is becoming idle speed after burn out.
I realise imidiedly that those filters are bad or not suitable for 20W50 mineral racing oils..
So i fit M-filters (Made in Finland) And made similar burn out etc test´s. No problem at all.

Engine is almost new, drived +8000km when i made it and ever had this type of problem with Fram, coopers, Bosch, Hengst filters..

Also our local race engine builder has got similar problem with His +400hp small block Chevy boat engine.. He use 2times of Mahle filters with 20w50 oil and have got over 1kg lower oil pressure than Fram filters when he drive like mad in water..
Now he go back from Fram and no problem.

I will estimate it will flow hot 20w50 oil in +700km and then it will flow oil in outflow hole in inside the filter and made some pressure problems when engine is becoming idling after heavy driving.. Outflow hole is shutting and then it try to start to flow normally but it cant because paper is to fine??

I dont believe that 3x mahle is bad, they are far to Fine for my oil and not suitable my engine revving cabability.. I think they would work in stock 3.5litre engine with 20w50 oil?

Update.

Now ~700km with this M-filter without issues..
I send e-mail to mahle and they will contact me again in this week bacause technical laboratory guy´s are in holiday.. They say it is strange proplem so they move my question to other place..

[ian_uk1975]

Sounds like a bypass valve issue? The bypass valve on the Mahle filter is probably calibrated to open at a different pressure drop across the filter.

A 20w/50 is a heavy oil to run in a cold climate like Finland... I would think about changing to a 10w/40 or 10w/30. You should select a viscosity based on oil pressure and oil temperature, which will be determined largely by the bearing clearances in the rods and mains and oil capacity/cooling, respectively.