BoatHowTo · video

What this video covers

Mixing different oil weights in a marine diesel engine — specifically adding 30W when only 15W-40 is available — is the question Nigel Calder addresses in this short Q&A with host Jan Attenstedt.0:24 Calder's position is direct: running an engine low on oil is worse than topping it up with a mismatched weight or brand.0:43 He draws on personal cruising experience where obtaining the exact specified oil was impossible, though he acknowledges he has no controlled scientific data to back the claim.Watch The practical guidance is to use whatever oil is available to keep the engine running, then switch back to the correct specification as soon as it can be sourced.1:23 Calder and Attenstedt invite listeners with harder technical evidence to contribute to the comments section of their marine diesel engine maintenance course.1:09 The core takeaway: oil compatibility matters, but an engine running on slightly wrong oil outlasts one running dry.

More from BoatHowTo

How to keep you TANK CLEAN in the days of BIODIESEL.. | Ask The Expert with NIGEL CALDERAug 2026PARALLELING Conductors for AMPACITY - is that SAFE?? | Ask The Expert with NIGEL CALDERAug 2026ENGINE OIL turns BLACK right after Oil Change?? | Ask The Expert with NIGEL CALDERAug 2026Same LAYUP RECOMMENDATIONS for FAME and HVO bio diesel? | Ask The Expert with NIGEL CALDERAug 2026

From BoatHowTo — see the channel’s boat, crew, and every analysed video.

The Sailing Directory Newsletter

One email with the fleet's best finds — the moments, boats, and stories worth your watch time. Enter your own address to get your own copy.