I just purchased this boat about a month or so ago, she has twin 1989 200hp Volvo Penta TAMD41A Diesels with around 446 hours on them. I am about to replace the racor spin on fuel filters and change the oil and filter, but I'm not sure what oil he was running in them. I have found milk crates in the enngine room with many new quarts of HD 30 oil, but I thought I read these engines run 15W40. Owner has no clue, as he had someone else do change the oil last fall, he only owned the boat for 3 years and put 14 hours on the engines... Anyway, if anyone knows the deal here, please let me know.. otherwise I will call Volvo rep on Monday. Maybe HD 30 is an alternate??