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MG MGB Technical - Oil filter quality and oil level

We all know, as has been discussed many times on this BBS, that the quality of the anti drainback valve in inverted spin on oil filters varies a lot. Changing the oil and filter on my converted ī64 engine today suddenly had me thinking:

I believe the MAX mark on the dipstick is supposed to indicate the correct maximum oil level with a full oil filter. I donīt know how much oil these filters normally contain, but guess it is enough to make quite a difference on the dipstick. So if my oil filter anti drainback valve is leaking, the correct maximum oil level when the car has been standing for a few days will be ABOVE the MAX mark, because the oil filter is close to empty. Right?

Next question is of course How Do You Know How Much Oil Has Been Leaking Out? I donīt - but perhaps best practise will be to always check the oil level when the engine is still hot after a drive, and not before I go on the next one, as I have used to?

Tore
Tore

Tore. All good thoughts, and all true. However, checking the oil level immediately after the engine is shut down can also cause problems. There is still oil in the passages and in the cylinder head which can take some time to drain down and fill the sump. Thus, it is difficult to guarantee the exact level of the oil and to determine what, if any, oil has leaked our of the filter.

I have used the Mann W917 oil filter for many years, since Bob Wilson recommended it here. I find that the oil pressure guage tends to start to come up in about two seconds and will show full oil pressure in about five seconds. These oil filters have to be special ordered in my area. When I found I was out and needed to do an oil change, I had to use a "direct replacement", the Mahle OC 28 filter. This filter began to show oil pressure at about the four second point and full pressure at six to seven seconds. This leads me to believe that the Mann filter has a better anti-drain back valve than the Mahle filter.

In truth, if you keep the oil level, cold, between the lines on the dipstick, you should have no problems.

Les
Les Bengtson

This thread was discussed on 24/09/2006

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