Number1&2 cylinder is misfiring,getting oil on number 1&2 sparkplug
There are two possible causes of this issue, and both deal with engine aging. The first, and most common, would be leaking valve stem seals. The dry out, shrink, and crack with age, and allow oil to run down the valve stem and be drawn into the combustion chamber, fouling the plug(s). Usually only plugs at the end of the engine where the top end drains to the sump has this problem since this is where oil will pool when the engine is shut down. The other possibility is worn or broken piston rings. This will allow oil from the sump, through the process of splash oiling, to work its way into the cylinder along the sides of the piston. If you are not experiencing major oil burning other than at start-up, then the simple solution is to keep a couple of clean, gapped plugs ready to swap out whenever the engine starts to miss. Clean the ones you remove and rotate them as needed. If the problem occurs too frequently, there are aftermarket oil foul preventers that can be installed, if space allows. Of course, the best solution is to find and repair the cause, but that, for older engines, is usually an overhaul or rebuild. Once you crack into the engine that deep, you need to decide what you are planning to do with the vehicle. If you plan to keep it long term, then a rebuild may be cost effective. Otherwise, short term measures will work without putting the engine at any greater risk.