Fuel Oil Ratios

[whichway]

Hi

I've got a 2 stroke 98 Johnson 175 (250 hrs) with the VRO disconnected so I am running 50:1 premix using Shell outboard oil. Sometimes it's a bit smokey if the wind blows the wrong way.

I know that some smaller capacity Yammys run 100:1 premix.

Question is - Has anyone tried to run a premix V4 or V6 motor at 100:1. What oil did you use and how long have you been doing it?

I copied the following from the Castrol website which suggests that they seem to think it is Ok (note the last line), but then they won't be paying for the motor rebuild if something doesn't work.


Castrol Biolube 100 is formulated with a synthetic high performance
base fluid and contains selected ashless additives to give excellent:
Lubricity and resistance to scuffing
Piston cleanliness and deposit control
Thermal stability
Resistance to plug fouling and pre-ignition
Anti-wear performance
Protection against rust and corrosion
Low temperature fluidity for oil injection systems
Proven 100:1 performance in OMC and Mercury engines in normal
service (unmodified engines).


Any advice would be appreciated

Regards

Whichway

[Kerry]

I would be erring on the side of too much oil is way way better then too little. Little smoke better than no smoke.

Effectively 50:1 is a lot safer than 100:1 as if the 100:1 ratio is specifically not spelt out in the handbook then I wouldn't be going anywhere near it.

Even with oil injection the higher ratio's are really induced at the lower revs but as the revs increase then normally so does the oil requirement and so the ratio is varied accordingly. In some engines the failure of the pump/throttle linkage etc will automatically put the oil pump in 50:1 by design.

No, your absolutely right your the one that will have to pay for any problems running 100:1 and that's something I wouldn't be risking.

By the way did you disconnect the VRO 'cause there was an actual problem or simply disconnect 'cause some old VRO models have given VRO a bad name in general?

Cheers, Kerry.

[bassfanatic5]

Have a talk to your johnson dealer about running Bombardier XD100 synthetic oil at 100:1. I have just brought a new etec and they adjusted and retagged it to run XD100 at half the amount it would use of TCW3 oil. My mate was with me and asked about running his outboard on XD100 at 100:1 pre mix and they said it would be allright.

[peterbo3]

The Castrol site claims that their product is OK at 100:1. Most VRO engines run at that ratio (approx) at lower revs so that claim needs to be taken with a grain of salt. I am sure that Shell & Penns, etc are also OK at 100:1 when the VRO system is mixing that ratio. I am also sure that at WOT you are better off at 50:1 regardless of the brand of oil. A little unburnt oil is a mile in front of a little roasted bearing.

[whichway]

Kerry

No problem with the VRO at the time, but several people advised me to disconnect it. It seems that after about five years, it can fail with no warning, and stop pumping oil into the motor altogether. This means a complete rebuild, not to mention being stuck out in the ocean without a motor.

Regards

Whichway

[Kerry]

Whichway, yes there was some issues with VRO in the past but from what I understand a lot of people apparently are still living in the past. This is quite a long time past and certainly pre 1998.

They have certainly appeared to have inherited a bad reputation. What's done is done but I'd be sticking with 50:1

Cheers, Kerry.