synthetic oil makes for easier starts on 90hp merc '99 model

wn6ngp

Petty Officer 1st Class
Joined
Aug 12, 2012
Messages
209
I just did a lot of boating on the bays so I used lots of fuel. In the past the motor has always been fussy about restarting after running a while and then being off for say 30 minutes or so like after a drift over a bay. Often I'd have make sure motor was trimmd vertically perfectly and squeeze bulb and choke a bit. On this trip that problem never happened. It restarted like a fuel injected version. I thought it was due to fresher fuel and clean carbs etc. This time around I had happened to buy some penzoil synthetic tcw3. After the penzoil got used up I went back to a generic tcw and the problem seemed to come back. So... I burned up that genric oil on the bay and when I got back I put Penzoil synthetic in it and now its back to very easy non-fussy restarts. Anyone else experience this?
 

Bigjoe530

Cadet
Joined
Nov 18, 2017
Messages
9
I am currently running the quicksilver but will have to give this a try, thanks for the info.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
I never experience a starting problem with Pennzoil synthetic. But then I never had a problem with the generic stuff either. Clean plugs, clean fuel, proper state of tune, good battery, proper starting procedure and oil should not make a difference.
 

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
15,417
I can run ?regular? oil in my 200. Loads up and smokes like a chimney. Semi and full synthetics no problem
 

wn6ngp

Petty Officer 1st Class
Joined
Aug 12, 2012
Messages
209
Did you happen to buy your fuel at different locations?
I started my adventure with a full 36 gallon tank of fuel and never added fuel to it.
I should add that this motor is an old school 3 carb 3 cyl motor. I really like the motor and as matter of fact when I see others with one just like it I have asked them how they like and they say its great except it is cold natured. Lots of enrichment to start it and then if it cools off same process. However, once I added this oil even my wife mentioned that it is restarting more easily. Kinda like my diesel truck, just hit the key and it starts. Not thinking about it I had some generic tcw and I put it in there the next day and it got fussy again. Always restarted but it took a bit more cranking. After a 25 mi trip the next day I added the synthetic and it slowly got better since it was a mixture. We'll see if this continues. For now I'm going to stick with the synthetic not sure if whether its penzoil makes a difference. It does smell a bit different than the generic tcw when it burns. I took another look at the oil jug, it is a blend not full synthetic.
 
Last edited:

Mercurylips

Petty Officer 2nd Class
Joined
Sep 23, 2015
Messages
189
I chanced on to the Pennzoil synthetic when I noticed my building supply store had a fairly well stocked marine section. Always had good luck with any other Pennzoil product that I used in my vehicles over the years. My old 77 500 starts right up each and every time so why would I change now? I use it in my snowblower, too.
 

merc850

Commander
Joined
Jul 7, 2010
Messages
2,022
I have a 1975 850 and I use Amsoil at 70:1 - I also use their gear lube, the combination works very well. I have a 1960 Merc 700 (Direct Reversing [R.R checkmate.jpg 850.jpg ]) that ran for 10 yrs.on 100:1 Amsoil and the performance was outstanding - pulling tube/skiers and other boats; synthetic oil is also environmentally friendly and is not made from crude oil. I recommend it to all owners, even old motors from the 50's will perform better.
 

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,286
Good to hear. Big fan of decent grade 2 stroke. Also a fan of a mineral blend though.
Normally fully synthetic has the opposite effect when starting. Always believed that old school 2 strokes love a good mineral blend lubricant. Keeps good compression and longer film of oil.
I personally use Rock oil MP3 tcw3 oil. It?s superb.
 

tommarvin

Ensign
Joined
Nov 22, 2015
Messages
999
We had a force 125hp started great ice cold everytime at the ramp, but would not hot start sometimes, had to wait 10-15 min for the failing ignition part to cool down, sold the boat before we ever figured it out. ,
 

GA_Boater

Honorary Moderator Emeritus
Joined
May 24, 2011
Messages
49,038
We had a force 125hp started great ice cold everytime at the ramp, but would not hot start sometimes, had to wait 10-15 min for the failing ignition part to cool down, sold the boat before we ever figured it out. ,

Since you never figured out why, this is just a story and no help for wn6ngp, is it?

Syn or a syn blend is supposed to be slippier than dino juice. Maybe the motor can turn over a hair faster to assist starting.
 

wn6ngp

Petty Officer 1st Class
Joined
Aug 12, 2012
Messages
209
My theory is that since synthetic oil maintains viscosity better over a wider range of temperatures that it makes the fuel mixture more consistent. Whereas, mineral oil thickens more at lower temperatures causing the mixture to be less than optimum at lower temps. In the end the why is not that important, if it works better then I'm going to stick with it. It could be that Penzoil does something special but I doubt it. Its just a reasonably priced synthetic.
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,047
Who cares about oil ?----There is so much confusion about how oil " works " inside a 2 stroke.----There are opinions everywhere.-----But does she have a sister who likes boating ?
 
Top