Westerbeke w52 yellow tint in oil inside valve cover

[hellosailor]

Any engine shop should have a resource for oil analysis. If you go online look for Blackstone Labs, they are the big independent lab in the US. For about $25 they'll mail you the complete kit including sample bottle and return mailer, so you just take the sample, pack it back up, and a week later you'll get an email with all the results as well as extensive comments. And, they keep your data on file so you can compare from one year to the next.
Shell, Quaker State, others used to have "fleet" programs at much lower prices, if there's a commercial trucking fleet in your area they may be able to hook you up.