Premix oil for 1986 Johnson 175 V6????

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Dec 20, 2007
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What is an excellent (synthetic) oil for this engine in regards to good qualities and less plug fouling? This engine uses the UL77V surface gap plug, and they seem to foul easily running at lower speeds. The VRO system has been removed, and I just premix 50:1, as recommended by the manufacturer. This would obviously also contribute the problem. The boat is an 1986 Cajun 18.5' bass/ski boat, and I use it primarily for fishing, so not much high speed running.
 

kenmyfam

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Re: Premix oil for 1986 Johnson 175 V6????

Might be a different issue than just the 2 stroke oil. What is the condition of all the plugs ???
 

jonesg

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Re: Premix oil for 1986 Johnson 175 V6????

What is an excellent (synthetic) oil for this engine in regards to good qualities and less plug fouling? This engine uses the UL77V surface gap plug, and they seem to foul easily running at lower speeds. The VRO system has been removed, and I just premix 50:1, as recommended by the manufacturer. This would obviously also contribute the problem. The boat is an 1986 Cajun 18.5' bass/ski boat, and I use it primarily for fishing, so not much high speed running.

My manual advises a wider gapped plug for extended trolling, is that the correct plug you are using?
 
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Re: Premix oil for 1986 Johnson 175 V6????

My manual advises a wider gapped plug for extended trolling, is that the correct plug you are using?

Johnson recommends either the UL77V or QUL77V (noise suppression) plug, both being surface gap.
 

dingbat

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Re: Premix oil for 1986 Johnson 175 V6????

What oil are you running now? I've tried a couple diffrent ones and keep going back to Merc Premium Plus and Evinrude HD50. The motor will load up a bit after 6-7 hours of trolling but not too bad. Never had a problem with fouling plugs.

This Spring they had a big sale at a local store on case lots of Pennzoil Premium Synthetic Blend. Figured I'd give t a try. I didn?t foul any plugs but the motor smoked a bit more and the motor was loading up noticeably more than before. Ended up dumping the last gallon or so of Pennzoil out of the tank and went back to HD50 to finish out the season.
 

James R

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Re: Premix oil for 1986 Johnson 175 V6????

What a shame you had bad results. If the price had been right I would have taken a couple of cases.
I run all my motors on Pensoil Synthetic premium blend and with excellent results at all speeds.
Less smoke than conventional oils and smooth and cool running. I have read reports on this oil and they indicate zero wear also. Running at 35:1 for break in works equally well.
I carefully measure the oil to fuel ratio and along with my many local fellow users ,have never had a problem. Wally world used to carry it but now I have to go to my Shelloil distributor. I buy a case at a time.
I recommend this oil.
 

tashasdaddy

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Re: Premix oil for 1986 Johnson 175 V6????

surface gap plugs are known for fouling, at slow speeds. i would go to QL77JC4 gapped plugs, gapped at .030. it will cut down on the fouling.
 

emdsapmgr

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Re: Premix oil for 1986 Johnson 175 V6????

The XD50 oil is a great oil for this engine. In addition to it's lubricating properties, it has the carbon guard additive already in the oil-which reduce carbon accumulation around the rings. This is probably one of the best oils for someone that trolls a lot.
 
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Re: Premix oil for 1986 Johnson 175 V6????

My oil could be the problem, too. I'll try either the Merc or Johnson/Evinrude oils and see if that makes a difference.

Thanks -
 

Genonbamagirl

Petty Officer 2nd Class
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Dec 9, 2008
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Re: Premix oil for 1986 Johnson 175 V6????

My oil could be the problem, too. I'll try either the Merc or Johnson/Evinrude oils and see if that makes a difference.

Thanks -

I've run a 130 and a 48 johnson at idle nearly all day long with no problems at all on the cheapest oil on the market. Cheap plugs as well. Just saying.
 

emdsapmgr

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Re: Premix oil for 1986 Johnson 175 V6????

With the poor quality of today's fuels, the engines in the crossflow family are susceptible to carbon accumulation around the ringsets-esp on engines with very high hours. Carbon is detrimental to long term durability and has been a primary cause of many powerhead failures. Bombardier Engine Tuner and/or their XD50 oil are both preventative measures designed to help reduce an carbon deposits.
 

ezeke

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Re: Premix oil for 1986 Johnson 175 V6????

With the poor quality of today's fuels, the engines in the crossflow family are susceptible to carbon accumulation around the ringsets-esp on engines with very high hours. Carbon is detrimental to long term durability and has been a primary cause of many powerhead failures. Bombardier Engine Tuner and/or their XD50 oil are both preventative measures designed to help reduce an carbon deposits.

Right, and don't forget that if your thermostats are not functioning properly or if you are lugging the engine by being overpropped, the engine will still develop carbon build-up.
 
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