The standard oil filter set up on the Series 2.25 engines is a bit fiddly and it can get a bit messy servicing the filter. A good solution is to use the oil filter adaptor from 90/110 (early Defenders) engines. The filter adaptor from a 2.5 petrol (17H) or diesel (12J) engine will bolt straight in place of the series one, very simple job to swap them over – this means you’ll be able to use 2.5 oil filters that will spin on and off like more modern vehicles. These oil filter adaptors are expensive to buy new (ETC5347 over £200!) but they come up on eBay and sell for around £30. You may even find a scrap 2.5 engine nearby, remember the cylinder head from the petrol 2.5 will also fit the 2.25 and besides having a higher compression ratio also has the bonus of hardened valve seats and valves so can be run on unleaded or LPG, so there’s a few useful bits for the series engine on the 2.5 engine if you can find one cheaply.