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2 cycle lubrication #4783437
06/10/18 08:52 PM
06/10/18 08:52 PM
Joined: Jan 2009
Posts: 1,352
texas
Burt Offline OP
Burt  Offline OP

Joined: Jan 2009
Posts: 1,352
texas
A small amount of gasoline in the oil of a four cycle engine is a bad thing, but some 2 cycle engines use mostly gasoline with a small amount of oil to provide adequate lubrication. I realize they are different systems but how do they get away with this? And of course no filtering other than in 2 cycles’ gas tank.


2011 RX350 58k miles
2015 Fiesta SFE eco-boost 28k miles
Re: 2 cycle lubrication [Re: Burt] #4783441
06/10/18 08:59 PM
06/10/18 08:59 PM
Joined: May 2012
Posts: 1,406
Georgia
AVB Offline
AVB  Offline

Joined: May 2012
Posts: 1,406
Georgia
Different materials and bearing types. Most modern 2 strokes use roller bearings.

Re: 2 cycle lubrication [Re: Burt] #4783443
06/10/18 09:02 PM
06/10/18 09:02 PM
Joined: Sep 2014
Posts: 1,531
Toronto Canada
WobblyElvis Online content
WobblyElvis  Online Content

Joined: Sep 2014
Posts: 1,531
Toronto Canada
Two stroke oil is a little different. It resists burning or it would gum up the rings and exhaust system very fast. When you see the blue/purple smoke from a two stroke, that's tiny droplets of oil in the air. The fuel/oil mixture is passed through the crankcase where it lubricates the crank and rod bearings which are roller or needle type. This kind of bearing can get by with far less oil. Some oil will settle in the crankcase where it is scavenged and returned to the intake port.

Last edited by WobblyElvis; 06/10/18 09:03 PM.
Re: 2 cycle lubrication [Re: WobblyElvis] #4783450
06/10/18 09:17 PM
06/10/18 09:17 PM
Joined: Dec 2006
Posts: 19,304
Dallas,Tx USA
aquariuscsm Offline
aquariuscsm  Offline

Joined: Dec 2006
Posts: 19,304
Dallas,Tx USA
Originally Posted By: WobblyElvis
When you see the blue/purple smoke from a two stroke, that's tiny droplets of oil in the air.


My old Yamaha DT175 would literally spray oil all over your back while you were riding it.


1996 Nissan 300ZX 5-speed,Arctic Pearl(#175 of 300)
Quaker State Ultimate Durability 10W30
2012 Honda Accord Coupe EX-L 2.4,auto,San Marino Red
Pennzoil Platinum 10W30

Re: 2 cycle lubrication [Re: Burt] #4783461
06/10/18 09:30 PM
06/10/18 09:30 PM
Joined: May 2012
Posts: 1,406
Georgia
AVB Offline
AVB  Offline

Joined: May 2012
Posts: 1,406
Georgia
Also fresh oil is constantly being sucked through the engine and flushed out of the exhaust. There is no dirty oil circulating. The air filter is super important though.

Re: 2 cycle lubrication [Re: Burt] #4783507
06/11/18 12:02 AM
06/11/18 12:02 AM
Joined: Jul 2003
Posts: 5,002
New Zealand
Silk Offline
Silk  Offline

Joined: Jul 2003
Posts: 5,002
New Zealand
There is also not much going through in a modern 2 stroke - my scooter has a cat. I'm currently on 1600km on a litre of oil, I calculated nearly 2000km to a litre, so still an unkown own at this stage.


1987 BMW R65 - Aegis SAE30
2005 Nissan Expert - 5W-40 Castrol Magnatec diesel.
1996 Volvo T5 - Penrite HPR15 - 15W-60. Ryco syntec filter.
Re: 2 cycle lubrication [Re: Silk] #4783527
06/11/18 01:12 AM
06/11/18 01:12 AM
Joined: Dec 2009
Posts: 26,551
Regina, Saskatchewan, Canada
Garak Offline
Garak  Offline

Joined: Dec 2009
Posts: 26,551
Regina, Saskatchewan, Canada
That's pretty amazing. That shows you how old my last two stroke was. wink


Plain, simple Garak.

2008 Infiniti G37 - Shell ROTELLA T6 Multi-Vehicle 5w-30, Wix 57356
1984 F-150 4.9L - Quaker State GB 10w-30, Wix 51515
Re: 2 cycle lubrication [Re: Burt] #4783617
06/11/18 07:01 AM
06/11/18 07:01 AM
Joined: May 2010
Posts: 1,220
Ocala, Florida
racin4ds Offline
racin4ds  Offline

Joined: May 2010
Posts: 1,220
Ocala, Florida
Doesn't this make the flashpoint of the 2T oil very important depending on the use of the engine? i.e. high revving race engines need higher flashpoints and low revving OPE low flashpoints?


Just say NO to thin oils and M1!
05 F350 Powerstroke
05 Hyundai Tucson
08 Legacy GT
Re: 2 cycle lubrication [Re: Burt] #4783658
06/11/18 07:59 AM
06/11/18 07:59 AM
Joined: May 2009
Posts: 12,342
N.H, U.S.A.
ARCOgraphite Offline
ARCOgraphite  Offline

Joined: May 2009
Posts: 12,342
N.H, U.S.A.
Its much worse now with alcohol in the fuel; acids and Ethanol make polyethylene precursors, can this happen in the engine? I say maybe given my filters plugging up the past decade.

Last edited by ARCOgraphite; 06/11/18 08:02 AM.

2019 VW Jetta S,6M OCI#0 1136mi-Castrol Edge Prof? VW508+OE Filter; '17 Subaru Crosstrek CVT OC#6 43467mi-Valvoline Adv 0w20 + SOA Filter
Re: 2 cycle lubrication [Re: ARCOgraphite] #4783690
06/11/18 08:43 AM
06/11/18 08:43 AM
Joined: Dec 2005
Posts: 10,682
Upper Midwest
kschachn Offline
kschachn  Offline

Joined: Dec 2005
Posts: 10,682
Upper Midwest
Originally Posted By: ARCOgraphite
Its much worse now with alcohol in the fuel; acids and Ethanol make polyethylene precursors, can this happen in the engine? I say maybe given my filters plugging up the past decade.

What? You say you think you're making a polymer and that's clogging up your filter?

If so, out of all the goofy things people attribute to EtOH in fuel that has to be the best one yet.


1994 BMW 530i, 241K
1996 Honda Accord, 267K
1999 Toyota Sienna, 409K
2000 Toyota ECHO, 280K
Re: 2 cycle lubrication [Re: Burt] #4785029
06/12/18 03:21 PM
06/12/18 03:21 PM
Joined: Apr 2009
Posts: 2,933
Canada
boraticus Offline
boraticus  Offline

Joined: Apr 2009
Posts: 2,933
Canada
"A small amount of gasoline in the oil of a four cycle engine is a bad thing"

Is it really? By the time the engine is up to temperature, any gasoline in the fuel will have evaporated.

You'd be surprised how many OPE engine have had or will get gasoline into the crankcase without any signs of related issues other than false oil reading due to increased volume the fuel adds while the engine is cold.

Re: 2 cycle lubrication [Re: Burt] #4786794
06/14/18 02:57 PM
06/14/18 02:57 PM
Joined: May 2010
Posts: 1,220
Ocala, Florida
racin4ds Offline
racin4ds  Offline

Joined: May 2010
Posts: 1,220
Ocala, Florida
Originally Posted By: Burt
A small amount of gasoline in the oil of a four cycle engine is a bad thing, but some 2 cycle engines use mostly gasoline with a small amount of oil to provide adequate lubrication. I realize they are different systems but how do they get away with this? And of course no filtering other than in 2 cycles’ gas tank.


LOL it doesn't hurt anything! Back years ago when we ran racing Karts they used the flathead briggs and stratton engines (5hp variant) and with a 34mm Tillotson carb and running pure methanol, I'd get on average 4-6 oz of methanol in the crankcase after each track session on my limited modified engines! Keep in mind these little things only held 14 oz of oil and turned 8500rpms!!! They lasted quite awhile before needing a rebuild too. A little gas in the oil surely won't hurt a thing!


Just say NO to thin oils and M1!
05 F350 Powerstroke
05 Hyundai Tucson
08 Legacy GT
Re: 2 cycle lubrication [Re: racin4ds] #4786839
06/14/18 03:41 PM
06/14/18 03:41 PM
Joined: Apr 2009
Posts: 2,933
Canada
boraticus Offline
boraticus  Offline

Joined: Apr 2009
Posts: 2,933
Canada
I'm surprised you'd have that much fuel in the crankcase once the oil is up to temperature. From my experience and what I've read, the gas in the oil usually cooks off when the engine is run for a while. Especially in an air cooled engine.

I agree, though that a bit of fuel in the oil is of very little consequence.

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