Gas in Oil. How bad is it?

[Plumber]

Hello from Northern Illinois...

My old 54 Plymouth Mopar flathead carbs always seems to flood over into the manifold and get gas in the oil. I installed a heat shield, but no luck, gas gets in the oil. You can smell it to. I guess it is such a common thing, that the service manual mentions it, and suggests an oil change interval sooner than the 2-3000 mark, that the breather tube and cap will evacuate some in vapor form.

While driving, the cars have great oil pressure.

My oil change consist of FormulaShell 10w30 and a NAPA 1030 filter on the restored Plymouth. The beater 54 runs National 5w30 with a bottle of STP oil treatment and no filter system.

They get about 500-600 miles a season on the motors (neither rebuilt). Next oil change I am sending in samples to see what is going on.

What kind of damage can gas do the engine components?

 

[Donald]

Not good. Gas is not a lubricant and will change the viscosity of the oil. And if E10, then you have some effects from the alcohol.

 

[dparm]

It will thin out the oil. I would recommend a short interval, and running something very stout that can take some fuel dilution.

 

[chubbs1]

Gas is not good but you are changing it out in an interval that should reduce the impact the fuel can/will have. I would use 10w30 in both and skip the STP oil treatment but I am sure it isnt hurting anything.

 

[y_p_w]

Why not an HD30 oil?

 

[Plumber]

Originally Posted By: y_p_w
Why not an HD30 oil?


Harder to find and not on sale.

I also add the STP to the beater Plymouth due to the fact the oil had not been changed in eons. I did not want anything to loosen up.

 

[y_p_w]

I mention an HD30 because they're allowed to have higher levels of ZDDP. They're not allowed to have VI improver, but a modern HD30 has much better multiweight properties than an HD30 from the 60s because of better basestocks.

At Wal-Mart all I can find is Super Tech. The big brands are increasingly harder to find in 30 wt at discount stores. At the major auto parts stores they have it in their house brands and occasionally in the big name brands.

I do remember maybe in 2005 buying a stash of assorted Chevron Supreme in API SL and SM. I got some of that in HD30 for a lawnmower for about 70 cents a quart after rebate. Man that was a sweet deal.

 

[Plumber]

I was told that if I wanted to increase ZDDP, then to add a quart or racing oil, say Valvoline. I know the STP snake oil bumps zinc, and is way cheaper than the racing oils. It also keeps the motor quiet.

 

[y_p_w]

If you want ZDDP, the one thing that specifically says it has it is Red Line breakin additive. If you've got an older car without a catalytic converter, go for it.

 

[Nick1994]

National Oil? Good God what is that!?

 

[y_p_w]

Originally Posted By: Nick1994
National Oil? Good God what is that!?

Some private label or bargain brand made by Pinnacle Oil.

http://eolcs.api.org/licenseAgreementService.aspx?id=172

Almost all of their current offerings under the National Premium brand are API SN licensed.

 

[bigt61]

I'd run a 20W-50, even diluted that will work. Just give it more warm up if you're driving in the winter.

 

[Astro14]

I'd go with Rotella...in 15w40.

Good regular price at WM. Good oil.

 

[Plumber]

Several have told me to run the Rotella.

 

[Garak]

Rotella is sensible, along with Valvoline's VR-1 or MaxLife, or QS Defy. I do know that among PCMOs, MaxLife did well with fuel dilution in my old F-150, keeping the pressure up where regular 5w30 oils failed.

 

[Clevy]

Originally Posted By: Plumber
I was told that if I wanted to increase ZDDP, then to add a quart or racing oil, say Valvoline. I know the STP snake oil bumps zinc, and is way cheaper than the racing oils. It also keeps the motor quiet.


Actually it doesn't. It effectively dilutes the add pack because the existing oil has higher zddp ppm levels.
And since you've got a fuel dilution problem I'd use a conventional 15w40 hdeo,changed often.
Can you rig up some form of crankcase venting that gets sucked into the intake thereby creating vacuum and perhaps helping the fuel evaporate faster?
If you've got a winter there I'd use a 10w30 conventional and plug it in.

 

[Fleetmon]

I use Rotella T1 in my stuff that performs best on a straight SAE 30....AA, Tractor Supply and others sell it and/or can get it for you....it's a pretty commonly used oil.

 

[Plumber]

These flatheads were designed to release fumes from the oil fill cap, or a breather tube on the side of the engine.

One thing I noticed is that the oil pressure is very good driving, then lowers to about 20 when at hot idle.

A while back, I had a ton of gas make it into the engine! The oil change looked like molton lead...must have cleaned the heck out of it.

 

[artificialist]

Originally Posted By: Fleetmon
I use Rotella T1 in my stuff that performs best on a straight SAE 30....AA, Tractor Supply and others sell it and/or can get it for you....it's a pretty commonly used oil.

The last time I saw T1 SAE30, it was rated CF and CF-2. No gasoline engine specs at all. I chose not to run it in my friend's gardening equipment that takes SAE30.