Oils ain't oils (but marketing is marketing)

[skronkman]

I'm just curious to know what oils people actually run in there 4 stroke outboards. I just serviced my 2009 115 Mercury and the manual says to use the special Mercury 25w40 FC-W oil. So I did, at $55 for 3.78 litre bottle! (Of course I needed 5 litres). That's $14.55 a litre. I'm very suspicious of marketing and branding and highly doubt this oil is any better than the Castrol RX diesel 15w40 I use in my car for $3.50 a litre. I actually called the Castrol technical help line and was told that the RX diesel oil would be perfectly fine in it and he agreed with my suspicion about it being more about marketing than formulation.

So im interested to hear what oil you guys use and or if you've had any issues. First hand experiences only please.

On a side note, one Mercury dealer I went to said they always put the Mercury 10w30 in all the outboard even the ones that say 25w40 in the manual. My old 1999 Honda stated 10w30 regular motor oil in the manual. Plenty of people on the internet state they use regular motor in their outboards without an issue. So I'm pretty convinced it's all in the marketing!

[smile0784]

Thats rediculas.
Murcery oil is normall more expensive.

[KeenAds]

I have done a lot of work on car engines, I can't see a 4 stroke outboard being too much different. But my 2 cents worth is use the correct oil viscosity the manual specifies and also use a well known brand. If you can get synthetic oil in the viscosity you need use that much better then regular oil.

[smile0784]

This is what i normally buy

Works out to $5.50 liter

[skronkman]

This is what i normally buy

Works out to $5.50 liter

That's 2 stroke oil, I'm talking about 4 stroke engine oil. The same marketing hoodoo and price mark up probably applies though if you buy the big marine (Mercury, Yamaha,etc) branded products. Although there is a difference in 2 stroke oil for air cooled and water cooled engines.

[smile0784]

Ok sorry
Same theory would apply wouldnt it

[Sinsemilla]

Just follow what the book says about viscosity for your engine and use a FULLY synthetic oil. Don't go for the cheapo home brand stuff but you also don't need to go for the top shelf stuff. and always remember to go up in viscosity once more hours are put on the engine and the engine becomes worn.

Cheers, Anth

[repspec]

im assuming a "diesel" style oil would be designed around diesel engines....so i would avoid using that on a petrol outboard.

55 for the 3.78ltrs is pricey...i know a dealer that has the standard 25w40 at $47 and the fully synthetic at $51

25w40 would be my choice in that... Those engines are based around the verado style and they use a 25w40/50 oil

[frozenpod]

Diesel oil contains extra detergent to help clean diesel engines. With the specific oils I have used branded diesel engine oil in petrol engines (confirmed with the manufacture before use) I have seen no negative effects on petrol engines.

We have had no issues using marine or regular car oil of the correct rating on the DF200 (not synthetic). But we do a lot of hrs and change the oil regularly.

[dazz999]

oils are oils companys spend tons of money to produce their product just read the manual for your engine and follow that on a side note no need for oil additives 20 year ago a rep came for a big oil company to talk about their product and said we spend big money on research of how products if it needed a additive we would have put it in