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Safe replacement for MerCruiser 25W-40 oil

Misty IV

Misty IV
in This Old Boat

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Misty IV

Misty IV

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I don't want to start an oil debate here, just asking for options.

My 2000 4.3L MerCruiser (replaced in 2005 with a rebuilt Jasper long block due to previous owner not winterizing properly) "requires" the 25W-40 oil from Quicksilver. I can no longer get it at my marine store and need options. I found a 25W-40 from Sierra Marine, but I know nothing about their oils. I'm familiar with their line of marine parts.

Can I safely get away with a 15W-40 from a well known oil company, like Pennzoil, Rotella, Valvoline, etc.? Is there anything special about the marine 4.3 engines that requires a special oil?

I've been using Purolator oil filters on the boat since I bought it in 2005 and haven't had any issues there. Input? Thanks!!

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rolmops

rolmops

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You can buy 25-40 at West Marine and Gander Mountain.

Instead you can use straight weight detergent automotive oil SAE 20 in freezing weather, SAE30 (cold weather) or SAE40 for use in areas of 50 degrees and up.

The 25 -40 can be used in all temperatures.

If your 4.3 has a catalitic converter you should use a syntetic 20W-40

Your purolator filters are fine.Baldwin filters (made in USA) are better. It is not the filtering quality that is different, it is the thickness of the outside wall that makes baldwin preferable.

Fram filters have a lesser reputation with stories of filters having collapsed or blown up

Edited by rolmops
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Misty IV

Misty IV

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West Marine is where I've always gotten the Mercury/MerCruiser oil before, but my store doesn't have it anymore, only the Sierra 25W-40.

I've heard the horror stories about Fram, as well, and I steer clear of them. I run Purolator in my car and truck, too.

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Misty IV

Misty IV

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I just went to the Mercury Marine website and the only 25W-40 oil they show is a synthetic blend for outboard 4-strokes, nothing for an inboard or stern drive.

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rolmops

rolmops

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Sierra will do ,remember that neither Mercury Quicksilver nor Sierra owns a refinery. They just buy from some oil company.

For Example,all the walmart Super Tech oil is Pennzoil.

Edited by rolmops
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Misty IV

Misty IV

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You're right. Their oil comes from a name brand refinery. I had just never heard of Sierra other than as a replacement part company, so got a little leery with an oil I know nothing about. I run Pennzoil in my car and truck and Purolator filters. Purolator also on the boat. Guess I'll give the Sierra a try.

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Chas0218

Chas0218

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Sierra will do ,remember that neither Mercury Quicksilver nor Sierra owns a refinery. They just buy from some oil company.

For Example,all the walmart Super Tech oil is Pennzoil.

Yup, what he said^

 

Back in the day Pennzoil was actually USA oil from P.A. now it is from overseas like most of the big name manufacturers.  I buy Brad Penn oil for my old Camaro and that is actually pulled out of P.A. and refined here in the US.

Edited by Chas0218
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rolmops

rolmops

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It always was my understanding that 15-40 is for diesel engines and not for gas engines. Can a Diesel Mechanic (Nick) please explain to me if there is a difference in lubrication needs or whether it has to do with constant rpm?

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lakebound88

lakebound88

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15-40 isn't just for diesel. It is a good oil all around. But it all comes down to brand specifics.. There's 30 and 30 HD. HD usually is in relation to diesel engines, unfortunately with all of the new emissions not only for gasoline engines, diesel as well, oils are slowly fading out the heavy zinc content due to it will cause catalytic systems to fail. I can go on forever on the emissions side of it.. For diesel systems.. I deal and work on them daily. I hate working on gas motors...

I run shell 30 wt with zinc additive. No issues... I would always stick with what your OEM recommends.. Especially if warranties are in place...

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Misty IV

Misty IV

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Wow, lots of great info. My warranty is long gone. Jasper gave a year and the engine was replaced in 2005. It currently has just shy of 300hrs on it and I've always used the MerCruiser 25W-40. I typically change oil and filter in the fall. Oil pressure has always been fantastic, even at idle and trolling for hours at 650rpm. I don't know what type of camshaft is in the engine or what was standard 10 years ago. If I use the diesel oil, will I be hurting anything if the extra zinc isn't needed for the cam?

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Misty IV

Misty IV

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I ended up going with the Rotella T 15W-40. I was able to get the 5qt jug and a new Purolator oil filter for $18.

I did happen to see the 25W-40 MerCruiser oil at another marine store at $42 for a jug. I think I'll be just fine with the Rotella. Thanks to everyone for the help and advice.

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