duckmnn
Member
- Jul 21, 2010
- 553
- Boat Info
- 270sundancer 1996
- Engines
- 454 B3
What's everybody running ? And seem to like in gas engines . Thanks
Opinions on engine oil 7.4
- Thread starter duckmnn
- Start date
paulswagelock
Well-Known Member
Any major brand 15w40 will be great.
Mike Blake
Active Member
- Jan 27, 2012
- 2,413
- Boat Info
- 89 340 Sundance all Raymarine.
- Engines
- Gas hogs 454X2.
Pennzoil Marine 40 weight
northshore
Well-Known Member
- Jan 17, 2011
- 2,094
- Boat Info
- 1989 340 Sundancer
Raymarine E90W Radar/Chartplotter
- Engines
- Twin 454 Mercruiser 340's
Awesome an oil 'discussion' right after a portable generator 'discussion'!
Anyways, Shell Rotella -straight 40w
Anyways, Shell Rotella -straight 40w
BillK2632
Well-Known Member
Here is the manual:
https://d3gqux9sl0z33u.cloudfront.n...nloads/224953/Mercruiser_v8_7.4_8.2_litre.pdf
Engine Oil
To help obtain optimum engine performance and to provide maximum protection, westrongly recommend the use of Quicksilver 4-Cycle 25W-40 Marine Engine Oil. This oil isa special blend of 25-weight and 40-weight oils for marine engines. If not available, a goodgrade, straight weight, detergent automotive oil of correct viscosity, with an APIclassification of SH, CF/CF-2, may be used.In those areas where Quicksilver 4-Cycle 25W-40 Marine Engine Oil or a recommendedstraight weight oil are not available, a multi-viscosity 20W-40 or, as a second but less preferablechoice, 20W-50, with API service ratings of SH, CF/CF-2 may be used.IMPORTANT: The use of non-detergent oils, multi-viscosity oils (other than Quicksilver25W-40 or a good quality 20W-40 or 20W-50), synthetic oils, low quality oils or oilsthat contain solid additives are specifically not recommended.The chart below is a guide to crankcase oil selection. The oil filter should always be changedwhen changing engine oil.
https://d3gqux9sl0z33u.cloudfront.n...nloads/224953/Mercruiser_v8_7.4_8.2_litre.pdf
Engine Oil
To help obtain optimum engine performance and to provide maximum protection, westrongly recommend the use of Quicksilver 4-Cycle 25W-40 Marine Engine Oil. This oil isa special blend of 25-weight and 40-weight oils for marine engines. If not available, a goodgrade, straight weight, detergent automotive oil of correct viscosity, with an APIclassification of SH, CF/CF-2, may be used.In those areas where Quicksilver 4-Cycle 25W-40 Marine Engine Oil or a recommendedstraight weight oil are not available, a multi-viscosity 20W-40 or, as a second but less preferablechoice, 20W-50, with API service ratings of SH, CF/CF-2 may be used.IMPORTANT: The use of non-detergent oils, multi-viscosity oils (other than Quicksilver25W-40 or a good quality 20W-40 or 20W-50), synthetic oils, low quality oils or oilsthat contain solid additives are specifically not recommended.The chart below is a guide to crankcase oil selection. The oil filter should always be changedwhen changing engine oil.
paulswagelock
Well-Known Member
API classification of SH, CF/CF-2 -> specification from 1996 and has been obsolete for almost 20 years now. Lubrication technology has come a long way since then.
I see you are in Illinois. If you start your boat when the ambient temps are in the 50's, 15w40. If you only start the engine when the ambient temps are in the 70's or higher, 15w40 or any straight weight 40 appropriate for gasoline engines and carrying an API certification.
You can always just use the Merc synblend oil that they currently sell. Is it the best oil ever - no. Is it fine - certainly. If you are cost minded, my recommendation stands. A gallon of major brand 15w40 is $11.99.
I see you are in Illinois. If you start your boat when the ambient temps are in the 50's, 15w40. If you only start the engine when the ambient temps are in the 70's or higher, 15w40 or any straight weight 40 appropriate for gasoline engines and carrying an API certification.
You can always just use the Merc synblend oil that they currently sell. Is it the best oil ever - no. Is it fine - certainly. If you are cost minded, my recommendation stands. A gallon of major brand 15w40 is $11.99.
hottoddie
Well-Known Member
- Jan 11, 2012
- 2,230
- Boat Info
- 1986 Sea Ray 390 EC
Garmin 4212 Chartplotter
Garmin 24 HD Radar
Garmin 546s Plotter
- Engines
- 454 Crusaders
If the engine has a flat tappet camshaft make sure the oil has the correct amount of zinc additives. I use 30w Valvoline VR1 racing oil in my flat tappet big blocks.
Dieseljeff
New Member
- Sep 14, 2013
- 303
- Boat Info
- 1994 290, 7.4 Bravo, Kohler 4kw
9.1 Hydro Force dinghy with a Mercury 9.8
04 Silverado 2500 D/A
- Engines
- 7.4 Mercruiser with Bravo III
I use straight weight 30 HD in my carbed 7.4...
I use 10w30 in my Honda genny. :grin: :smt021
I tried straight 30 but the low oil light would come on when cold starting.
Jeff
I use 10w30 in my Honda genny. :grin: :smt021
I tried straight 30 but the low oil light would come on when cold starting.
Jeff
Last edited:
duckmnn
Member
- Jul 21, 2010
- 553
- Boat Info
- 270sundancer 1996
- Engines
- 454 B3
paulswagelock
Well-Known Member
Rotella is a major brand 15w40 dual certified oil as I mentioned above. It will work just fine.
Snapon24
Active Member
- Sep 16, 2018
- 117
- Boat Info
- 1988 340 Express Cruiser
- Engines
- Twin FWC 7.4L Mercruisers w/Borg Warner straight drives
Looking for best oil option for my carbed 7.4L Mercruisers in my 1988 340 EC. After reading a few threads on here im between the 25W40 Quicksilver oil and Rotella 15W40. I would imagine I cant go wrong with the Quicksilver oil since its recommended by Mercruiser but Ive read about it not having additives that the older engines need. Can anybody clarify this? Or make another suggestion?
Rusted Nut
Member
I use Rotella in everything diesel trucks and tractors boats, cars. Specific oils for Pwc and motorcycles for s/c and wet clutches.
Just pulled apart my (2) 1993 7.4’s @1500hrs. I put ninety hours on them. Port was redone in 99, stb had original bearings. Both were clean no sludge main and rods meet specs. First owner I don’t know what was used second owner had pennzoil on board. Did oil analysis for both seasons I had it. You want high zddp because of those flat tapper cams you have. I can recommend a oil analysis if you really want to see what’s going on. blackstone labs is great.
Just pulled apart my (2) 1993 7.4’s @1500hrs. I put ninety hours on them. Port was redone in 99, stb had original bearings. Both were clean no sludge main and rods meet specs. First owner I don’t know what was used second owner had pennzoil on board. Did oil analysis for both seasons I had it. You want high zddp because of those flat tapper cams you have. I can recommend a oil analysis if you really want to see what’s going on. blackstone labs is great.
Snapon24
Active Member
- Sep 16, 2018
- 117
- Boat Info
- 1988 340 Express Cruiser
- Engines
- Twin FWC 7.4L Mercruisers w/Borg Warner straight drives
Ive read that the Rotella has the higher zddp for my engine and thats why people use it. I was leaning towards the Rotella. I don't know what the previous owners used. The engines have 1400hrs on them but they seem to be in good shape so Id like to get as much time as possible out of them before rebuild or long blocks. As far as oil analysis, I work at a Cat dealer and we have an in-house oil analysis lab so Im going to give them samples to test. Thank you for the input.
