BoatHowTo · video

What this video covers

Nigel Calder addresses whether an aging, oil-leaking diesel engine should use single-weight oil instead of the manufacturer-specified multi-grade.0:10 The question arises from a boat whose manual calls for 15W-40 but whose previous owner used single-weight 30W.0:20 Calder's answer: follow the engine manufacturer's specification first.0:31 When the recommended oil is unavailable, a single-grade 30W is the historical default for diesel engines and an acceptable substitute.0:57 The critical check is the API service category on the label — a "C" designation indicates a compression-ignition (diesel) engine oil; an "S" designation marks a gasoline engine oil with different additives, which is not appropriate.0:58 An oil labeled with both "C" and "S" is acceptable for diesel use.1:24 Calder does not confirm that switching to single-weight oil specifically reduces leakage through valve stem seals; the video contains no evidence supporting that claim. Jan Attenstedt notes that BoatHowTo.com offers a full Marine Diesel Engine Maintenance course covering oil selection in detail.1:35

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