Could oil effect performance?

[tayzak15]

Hey guys. I currently have a 200Verado L4 that I was turning around 6200 Rpm and 52-53 mph last season. Last season I was running mercury 25w-50 oil in it but this year I switch to 25w-40 quicksilver and my performance has dropped about 200rpm and 2 or so mph with nothing else changed. Spark plugs look fine and the engine runs smooth still with no funny sounds. I haven’t added any weight to the boat from last year. I’m just wondering if the cheaper brand of oil I’m using is causing the minor performance loss or if I should start looking elsewhere?

[OldTimer57]

Quicksilver is not "cheaper oil". It is the same as mercury oil because it IS mercury oil. I'd suspect this is more of an air density / temp issue, not an oil issue. I would be looking elsewhere, but first compare air temp between the two outings where you noticed the RPM loss.

[tayzak15]

Quicksilver is not "cheaper oil". It is the same as mercury oil because it IS mercury oil. I'd suspect this is more of an air density / temp issue, not an oil issue. I would be looking elsewhere, but first compare air temp between the two outings where you noticed the RPM loss.

I've ran the engine at the same performance level for the past three years then at the start of this year I had changed the oil to quicksilver and now I'm down about 200 rpm. Another thing I was thinking about was that I had forgot to add stabilizer to my gas last fall with about half a tank left. I added premium at the start of this season and I've been out on about 6 trips now so I'd imagine I would've burnt through any bad gas that would've been left in there but who knows.

[Northwoodswalleye]

Check the prop for damage?

[tayzak15]

Check the prop for damage?

The prop itself is identical to last year. I did change gear oil this spring and everything seemed fine. I may double check the hub this week though.

[kry29]

Oil level will effect performance. If it's to high it will get sluggish

[mdtritn21]

Probably the old gas then you added 93 octane that the motor wasn't designed to run since high octane burns at a lower temp than the 87 does. Burn it off put new plugs in it and new 87 octane gas.

[tayzak15]

Probably the old gas then you added 93 octane that the motor wasn't designed to run since high octane burns at a lower temp than the 87 does. Burn it off put new plugs in it and new 87 octane gas.

Do you think I can get away with just burning off the gas and not replacing the plugs? I checked the top two plugs and they looked perfect still, however I have not checked the bottom 2 since they seem like a royal Pain to get to unless I'm missing an easy step to access them on the L4 Verado?

[BMCD]

I would not think dropping from 50-40 would effect performance negatively. Yes oil can effect performance, But i agree that you prolly need to look at other things first. I thought verados can run whatever fuel you choose. they will adjust.

[berudd]

Oil level will effect performance. If it's to high it will get sluggish

Yeah, I was going to say that. It is definitely the cause in automotive engines where high oil levels can cause excessive drag on the crankcase.

[Tim Kelly]

Old gas plus the wrong gas sounds the most likely issue.

[SilverFox579]

The Mercury oil is 25w-40 just like Quicksilver.

[tayzak15]

Old gas plus the wrong gas sounds the most likely issue.

I hope that's the issue. I've been out about 7-8 times this year but have constantly be retopping the fuel when it got to half a tank. I will run it down near empty for the next trip or so and refill with fresh gas from there. Hopefully it improves!

[EuropeanAM]

Ok... let's get some perspective. You were running the 25w50 oil (Original VERADO Oil, now called Mercury Racing Fourstroke). Perfectly acceptable, though 25W40 Mercury or Quicksilver 4-stroke is also fine (and less expensive).

I would not expect any significant or discernable performance difference between them provided that the LEVEL is correct (1/4 into the safe zone, when checked as described in the Engine Owner's Manual.

Octane and Spark Plugs are likely contributors. I often see plugs that "look" to be ok but in fact are not firing properly (especially in the lower two cylinders).

If you would, please take a moment to review the Announcements at the top of the Forum, and be sure to provide the Required Info when posting. Thanks!

[tayzak15]

Well. I cleaned the plugs and emptied the water/fuel separator this week (there was a bit of water) and my engine was running stronger than ever again! not sure which of the things improved it, but engine is running perfect again!

[kry29]

If that was the case I would be changing the plugs and filters for new ones