The concern is that synthetic (with their detergents) will clean out the ring grooves and cause excessive blow-by and increase oil burn. Regular diesel oils - even single weight oils - have had detergent additives for many years. Certainly since I was an apprentice (in the '60's). So unless the Yanmar is pre '60's, I wouldn't be too concerned. Most of this concern stems from gas engine experience, where detergent additives came much later and there has been real experiences of gas engines loosing compression after a change to synthetic.
Sam Salter CandC 26 Liquorice Ghost Lake Alberta > On Jul 23, 2017, at 5:09 PM, Marek Dziedzic via CnC-List > <cnc-list@cnc-list.com> wrote: > > Mike, > > There are some reports that synthetic oil may dissolve some of the residues > left on different parts, which may lead to sudden increase of the oil usage. > Of course, this applies to older engines. The general rule of thumb is that > if you used non-synthetic oils in the past (and did it for years) you may > want to stay with the same kind. If you used synthetics, there should be no > issue switching to non-synthetic. > > My personal experience is limited to a single car in the past, where I > changed from normal to synthetic (the car was driven hard) and I ended up > with an engine that burned about 1-1.5 l (1-2 qt.) of oil for 1000 km. > > I don't believe that you could use oil that is "too good" for the engine. As > long as it is the same grade, it should work fine. > > In your case I would monitor how much oil is staying in the engine (and how > much you burn). > > Good luck > > Marek > 1994 C270 "Legato" > Ottawa, ON > > -----Original Message----- > From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Hoyt, Mike > via CnC-List > Sent: Sunday, July 23, 2017 11:45 > To: cnc-list@cnc-list.com > Cc: Hoyt, Mike <mike.h...@impgroup.com> > Subject: Stus-List synthetic oil > > I had my brother pick up 15w40 for me last week. Changed oil today and when > old oil drained realized he bought synthetic 15w40. Have outing today and no > time to get regular oil. > > Plan to drain and change later this week to non synthetic > > Is this an issue? > > Yanmar 3gm30f > _______________________________________________ > > This list is supported by the generous donations of our members. If you wish > to make a contribution to offset our costs, please go to: > https://www.paypal.me/stumurray > > All Contributions are greatly appreciated! > > _______________________________________________ > > This list is supported by the generous donations of our members. If you wish > to make a contribution to offset our costs, please go to: > https://www.paypal.me/stumurray > > All Contributions are greatly appreciated! _______________________________________________ This list is supported by the generous donations of our members. If you wish to make a contribution to offset our costs, please go to: https://www.paypal.me/stumurray All Contributions are greatly appreciated!