The oil filter’s being a tad awkward
QAccording to the service manual my 1991 BMC engine requires an oil change every 150 hours, but it doesn’t mention the oil filter. I have a spin-on filter conversion but it is too long to unscrew from the filter head and changing it makes a horrible mess: is it necessary to change the filter at the same time or would once a year be okay? ALAN CLARKE, via email
AThe filter has a bypass valve in it, so if it blocks this opens (you have no way of knowing if this happens) and unfiltered oil is directed to the engine with the attendant risk of excess wear. So (quite apart from laying myself open to litigation by going against the manufacturer’s recommendations) I cannot advise reducing the filter change intervals.
Ask whoever supplied the filter conversion for the correct filter number. Yours may have been changed at some time for a longer one.
Is the filter head still secured on the block by the original two bolts? If so, get some filter head to block gaskets, and instead of taking the filter off the head, undo these two bolts. Then lift the whole assembly away to somewhere that you can undo the centre bolt over a tray or bowl. Scrape the remains of the old gasket from the faces before fitting a new one.