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MG MGB Technical - An oil level question
|Throughout the years I would check the oil when the engine was hot and add as needed. On trips that meant at gas stations after gassing up, etc.|
Now I've noticed if I check the oil with the engine hot/warm the level is right at the top mark. If I check the engine cold the next morning the level is now past the top mark and at the M of Max on the dipstick.
If I let out some oil when the engine is cold and get it to the top mark I see that the oil level when the engine is hot is now down towards the lower mark.
Is this normal? Have I not noticed this all these years?
What should I use as a measure to get the oil to the right level?
|For an accurate measurement you should wait 5-10 minutes after a run before you check.|
It is most accurate to check in the morning before startup because the sump now has collected all of the oil.
|I have to say that '5-10 minutes after a run' and 'in the morning before startup' cannot both be 'accurate'.|
Oil can take some time to drain back to the sump after switch off, some manufacturers recommend checking cold and others hot just a few minutes after switch-off. My glovebox handbook doesn't say for checking, but for refilling says to check a few minutes after switching off. But it's not that critical and is why there is a Min and a Max mark i.e. you maintain it between the two. You wouldn't want it either above Max or below Min when hot.
|BL workshop manual says 'a few minutes'
|The driver's handbook says "always check the oil before a long journey", which probably means checking it cold.|
Checking it hot, a few minutes should be sufficient for hot oil to drain back to the sump.
After changing the oil and refilling, the cold oil would take a long time to drain back. Running the engine for a short while will warm the oil, helping it to drain, as well as filling the filter.
I always check it cold, apart from after an oil change.
|Dave O'Neill 2|
|Thanks everyone! I drained a bit out today after the oil change to get it in the proper place on the dipstick.|
|If you have an inverted oil filter, could it be that the oil is leaking out into the sump, so that the level increases? This will happen with a faulty non return valve.|
|Tore, that's interesting because I never recall this happening in the past. But isn't the non-return valve inside the oil filter?|
It is inverted. 1971
|Yes. The quality of the cartridge oil filters, if that is what you have, is varying. I have converted my ´63 MGB to cartridge filters, and have noticed big differences in how fast the oil pressure is coming up when starting from cold.|
In some filters the valve is not working well at all, it takes several seconds to get oil pressure even if the car has only been standing for a day or so, because the filter is almost empty. With the Mann W 916/1 filter I am using now I get good oil pressure immediately after starting, even if the car has been standing for a couple of weeks.
|I used to use K&N forever and then they changed the specs without telling any of us and many suffered no OP as a result of the inverted holder tube being blocked.|
Someone who used to work in the industry insisted that Purolator PL20195 was the best available and I switched to that. Don't see much of a difference.
|Mann oil filters seem to be the best for having a decent non return valve. W916 I seem to remember. It's also a Volvo item as well.|
|Thx! I'll look into it.|
|There is a Volvo filter that fits the MGB - 3517857-3, however that is shorter than the Mann W916/1, it's equivalent to the Mann 917/1. The longer one is preferable as it has a fighting chance of having more filtration area.|
|I'll look for a cross index number as that Mann number only comes up for the UK. For years I was happy with K&N. Too bad they changed the specs.|
|Bear in mind the cross-index may well list everything that physically fits, regardless of quality. One list I have contains 126!|
This thread was discussed between 07/10/2015 and 15/10/2015
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