4HP B&S Quatum, watery oil?

[EloManga]

My dad found the above mower and got it to start on 1 pull and amazingly, it ran well. Though, there seems to be some kind of throttle problem. First, he noticed that it sucked gas like crazy. Then I changed the spark plug and air filter. I then drained the oil, or so I thought (it was oil that came out from where you add it) and after putting new oil, it was still black and watery? I then found the drain plug underneath and just drained it. Again, it was watery and black? It leaves me scratching my head. How can it be watery and black for that matter, I just changed it!!!!!
So, aside from the possibility of the carb being dirty, does it really matter what kind of oil I use? I was thinking, I have some Mobil 7500 Clean 5W30, you think that would be ok and could possibly clean up the engine a bit?

 

[dwendt44]

You could use it for a short time.
Most B&S engines call for straight 30; some for 10W-30.
If the float is set wrong, you could be getting raw fuel into the oil; not good.

 

[EloManga]

I figured there was something wrong with the carb, since I couldn't run it at wot. I don't know carb's so I guess I'll have to get my neighbour on it pronto.
As for the oil, yeah, we buy straight 30 weight oil. 5w30 wouldn't be good, eh?

 

[Quest]

don't hesitate to get your carb fixed (rebuilt) so as to restore proper performance and functionality.

For air-cooled engines, your best bet would be ether straight weight SAE30 or HDEO like 15W40 (Delo,etc.)

5W30 is no good for air-cooled engine such as higher hp B&S.

 

[1999nick]

Then why does B&S recommend and sell under their brand name 5W30 synthetic oil for use in their engines? They do say that dino multigrades can cause oil consumption in some cases.

Personally, I have always used M1 5W30 in my Craftsman mower with the Honda 5.5 hp OHC engine. It gets used 60+ hours a year, and has never consumed any oil between yearly changes. Last year, I even tried 0W30 in it, and same story: no consumption in 64.7 hours of use. Lighter, easier to sling oils work much better in these small air-cooled engines that use an oil slinger for lubrication.

 

[tmorris1]

I am currently running synthetic 5W30 in my 4hp Briggs Quantum and I have to say that the engine runs stronger than ever with the light oil. I have had no no oil consumption to speak of yet this year. It starts easier and seems to labor a little less in taller thick grass. It is a mulcher and I always thought the 4hp was a little small, but the 5W30 seems to help a little.

 

[Cujet]

Some Briggs engage the choke at WOT. Make sure of this.

I suggest M1 15-50 or a good 30W oil for air cooled engines.

Chris

 

[ebaker]

Your choke is probably on, maybe it's being operated with the throttle advanced past full throttle in the choke position. I think any 5w30, 10w30, 10w40, or straight 300 will work fine. Oil related failures are very rare, as long as you don't run them dry.
Also check the air filter.

[ July 05, 2006, 10:29 AM: Message edited by: ebaker ]

 

[1999nick]

quote:

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Originally posted by Cujet:
Some Briggs engage the choke at WOT. Make sure of this.

I suggest M1 15-50 or a good 30W oil for air cooled engines.

Chris

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And I repeat: lighter, easier to sling oils work much better in these small air-cooled engines that use an oil slinger for lubrication. Case in point is my Craftsman mower with the 5.5 hp OHC Honda engine mentioned above. I bought it in 2000, and, according to the hour meter I installed on it, it gets used 60 to 70 hours a year. Last year, it was 64.7 hours between yearly oil changes.

It has always had Mobil 1 5W30 with the exception of last year, when I tried M1 0W30. No difference, still used no oil. This month (July 2006) marks 6 years of use with this mower,
and it has never used ANY oil between annual changes. It has not been trouble free; I have replaced all 4 wheels because the rears split apart and the fronts wore off smooth and had no traction. I also had to replace the transmission, as the driven gear was completely worn out. In years past, I would have tossed out a mower requiring these repairs, but I want to see just how long this Honda engine will last on one oil change a year. (The manual says to change oil every 25 hours).