Mobil One Synthetic

[Serendipity]

Guys.
Quick question, I have no idea what type oil has been used in my engines over the years. I have about 80 hours on the oil and neither engine has used a drop since I got the boat about 2 1/2 years ago. Current hours are 472 and 477.
I would like to change the oil before this spring and ya know the 7.4 MPI Mercs better than anyone.

Is it safe to use Mobil One Synthetic and call me old school, maybe even overkill, but I also like to add a small bottle of Slick 50 Synthetic which I have used since 1989.
Is there another oil I should be using instead?

I would imagine the transmission fluid is changed at the same time?
What guidelines do ya normally go by?

Thanks in advance and I sent up some more money. I hope ya are having an awesome weekend.

[bud37]

Oh my.....whatever oil you decide upon..... "no additive required"......In my opinion there should be no need for additives, the oils will have all they need. ......

[km1125]

I'm a big fan of Mobil One and used 15-50 in all my heavy-duty engines, including the Crusaders on the boat.

[Midnightsun]

I am partial, it's a brand name. Is Mobile One really better than brand X full synthetic in the same viscosity? One thing for sure is the marketing behind Mobile One far surpasses all other brands.

That being said, I just picked up a 5L jug of "Super Tech" 0-40 full synthetic oil which is Walmarts brand. Need to do an oil change on the Mercedes, was on special for $14.77 CDN. Says right on the jug "European Formula" plus it says meets Mercedes XXXX certification which is the one required for my vehicle.

Boat engines are old school, synthetic will not hurt but is not required, no additives required either. 15w 40 oil is what I always used in my boat engines.

[Tireless]

I actually use Shell Rotella T4, 15W40 in all my marine stuff. Not sure of anyone using synthetic in their boats, not saying there is any downside to it, other than cost. I have been told that it is not advisable on the older engines, for some reason. There are guys on here that know a lot more than I do about oils.

I know the dealership uses synthetic in my Lexus and Camaro, but they are newer vintage.

Greg

[SunsetSteve]

I have 2 4l. jugs of Rotella T4 15-40 left over from my diesel Albin and am looking for emotional support for putting in to my new-to-me Riv in the spring. This helps. Also -I have found that synth in older vehicles - which is what I often drive to the scrap yard - slips out more easily and seems to burn off faster than dino. Considering the relatively low hours I anticipate experiencing on the boat, I will stick to dino.

SLick 50 is questionable:
https://www.quickhonda.net/teflon.htm

[Midnightsun]

I have always used Rotella T4 15w 40 in all my gas boat engines if that makes you feel any better. Just trying to give you some emotional support.

[g36]

You can search this forum and find lots of topics on oil suggestions, all are interesting reads

[Serendipity]

Thanks everyone and it does sound like I will hold off on the Slick 50 or Teflon

[tomschauer]

The 1998 7.4's are gm vortech engines with roller cams and lifters. So these are not really "old school", but they do not have variable valve timing and such as newer engines. The cars and trucks GM installed these vortech engines have labels and fill caps recommending Mobile1.
Mercruiser required a mercruiser synthetic blend of 25/40. I run mobile1 15/50 in my 1998 7.4 horizons.
If you run any good quality oil that meets the OEM specs, and stick with that brand on decent change intervals, you should be good.
I would not add anything to the oil, such as slick 50.
Oil contains additives, when you statr mixing and and matching oils and additives, that's when you start building sludge and have problems.