russ
Well-Known Member
Does my inboard mercruiser petrol engine really need to use marine oil or can I use any synthetic 4-cycle 25w-40 oil?
Engine oil
- Thread starter russ
- Start date
rafiki_
Well-Known Member
You can use any oil that meets the spec that Mercruiser state. Generally, so called marine oils are rebranded automotive oils. No need to buy Quicksilver oil, the Merc brand, as long as you use the correct spec.
lanerboy
Well-Known Member
I have just serviced a 6hp Suzuki outboard and the oil spec was just 5w 30 semi synthetic oil and I just used normal car oil as suggested by the dealer I spoke to
Spi D
...
Oil specs are updated frequently and recent products easily match those required re. older engine manuals.
Check the recommended standard as mentioned. If not new(ish) your engine might not benefit from synthetic - some users actally see an increase in consumption because tolerances in older designs are not meant to cope with such light running lube
Check the recommended standard as mentioned. If not new(ish) your engine might not benefit from synthetic - some users actally see an increase in consumption because tolerances in older designs are not meant to cope with such light running lube
Last edited:
spannerman
Well-Known Member
Volvo have recently approved the use of their diesel oil in their petrol engines, so that's what I've been running my Mercruiser 350 Magnum, and the wifes Saab on with no ill effects.
lynall
Well-Known Member
omega2
Well-Known Member
MapisM
Well-Known Member
Not only it doesn't NEED it, but if your engine could speak, it would advise you against it.
The OEM Merc oil is not even a fully synthetic oil, but just a cheap blend sold at ridiculous prices.
Besides, 25W is an AWFUL specification, for one of the most important moments of lubrication - i.e. cold cranking.
I always used Mobil 1 0W-40 on both my 350 and 496 engines.
In the US, that's one of the most common recommendations (together with AMSOIL of the same viscosity) which you will get frm any reputable engineer.
And I'm not only talking of basic engines, but also for the 525 EFI, all the way up to supercharged blocks.
That aside, since you're speaking of Merc oil, you might be interested to know that their outdrives oil is even worse, and should be avoided like the plague.
See this thread for further details:
http://www.ybw.com/forums/showthread.php?330662
Actually, you said it's an inboard engine, but I'm now guessing that you actually meant inboard just as opposed to outboard.
In fact, I've yet to see one single Merc petrol block used as a pure inboard, and not mated to an outdrive.
All that said, you might wish to stick to Merc OEM oils if your warranty is not yet expired.
There's not a snowball chance in hell that Merc oils will protect your engine/outdrive better than most other oils, but they might use that as an excuse for not honouring the warranty,
B58
Well-Known Member
There is no need to use synthetic oil, just use strait forward mineral based oil, Mercury do not use fully synthetic oil anymore even for there EC models.
Synthetic oil has a mineral base oil anyway, the oil manufacturer only add a pack of synthetic additives!
With an engine design going back to the 50's you are not going to gain any extra benefits!
Synthetic oil has a mineral base oil anyway, the oil manufacturer only add a pack of synthetic additives!
With an engine design going back to the 50's you are not going to gain any extra benefits!
oldgit
Well-Known Member
Thats good to know as Ive been running diesel oils in petrol motors for years
Comma fleet oil has been lubricating my world for years, but then we are not running D12 or V16s
Actually I fib my Smart Roadster is running on Comma fully synthetic
macnorton
Well-Known Member
A friend had a Searay 390E with two of them on shafts (factory built)
MapisM
Well-Known Member
Well I didn't say there's a NEED for it, did I? Arguably, there's no need to use pleasure boats at all....
But fwiw, these days synthetic would be my choice for any high(ish) revving petrol block, regardless of when it was designed.
And particularly when used in a boat, where it could run for a long time at high rev/high load.
Oh, and it's not true that all syn oils have a mineral base. Mobil 1 is Group IV for instance, but there are many others.
MapisM
Well-Known Member
Yep, I'm aware that this setup exists.
I just meant that it's as rare as hen's teeth, particularly this side of the Pond...
...hence my guess that the OP might have referred to a sterndrive setup, even if he said inboard.
Scarron
Well-Known Member
I am using fully synthetic Shell Helix Ultra 15w-50 in mine [started life as a 385hp Mercruiser 454 Magnum but with a bit of fettling is now making closer to 500hp] Well worth the upgrade from the standard 25w-40 mineral oil.
I bought a pack of 12 x 1L from Smith and Allen for £53 http://www.smithandallan.com/prodpage.aspx?id=2785 excellent service and an unbeatable price. Make sure you also put a decent quality filter on it as well, I use K&N.
I bought a pack of 12 x 1L from Smith and Allen for £53 http://www.smithandallan.com/prodpage.aspx?id=2785 excellent service and an unbeatable price. Make sure you also put a decent quality filter on it as well, I use K&N.
MapisM
Well-Known Member
Wow, do tell, I for one would be interested to hear more!
Whipple SC, by chance? It surely takes some hardware, on top of "a bit of fettling"
, to add 100+ ponies...!Scarron
Well-Known Member
Wow, do tell, I for one would be interested to hear more!
Whipple SC, by chance? It surely takes some hardware, on top of "a bit of fettling"
Nope, no forced induction. Having had a cam belt snap on one of my old Volvo AQ171s [they all do that eventually] I decided to re-engine my old tub and go from twins to a single engine, I bought a S/H Mercruiser 454 Mag MPI, to cut a long story short it wasn't in as good condition as advertised. So we stripped it to do a head job and crank bearing shells etc. it all started with the bright idea of just changing the cam to perk it up a little bit, things are never simple tho... especially when being goaded on by BurgundyBen! - without whose help I couldn't have put it together [or spent so much..] thanks chum.
So I started off with a custom ground hydraulic roller cam from Bob Madara in the States, but apparently you can't just swap a cam on it's own?
So it wasn't long before UPS started to arrive on a daily basis, delivering a succession of boxes containing variously; an adjustable billet duplex timing chain set, aftermarket lifters, pushrods, billet roller rockers, Manley Inconel valves, springs etc. upgraded oil pump, and cooler with oil stat. [this internet can be dangerous for your wallet]
Then of course coz the fuel infection need remapping to suit that lot it somehow seemed easier just to buy a new Edelbrock Vic Junior inlet manifold and a fully programmable Holley HP-EFI system. And of course as the exhaust seemed questionable we put a pair of Keith Eickert cast aluminium equal length headers and dry tailpipes.
Phew hope you weren't too bored by that MapisM?