The Stovebolt Site Forums The Shop Area Engine Shop oil bath breather

What is everyone using for oil in a oil bath breather. Can't seem to find 50wt oil. could i use 90wt.

NAPA has 50W oil.

The weight of the oil is important in an oil bath air cleaner.

O'Reilly, Autozone and Advance Auto have 50W oil (non racing grade).

When I was using the oil bath on my '38 I just used 30 weight motor oil. That's all the manual called out for.

Engine oil is designated for the standard oil-wetted air cleaner described on the page at the link above.

On the next page in the 1938 Shop Manual, in reference to the oil bath air cleaner, it states that S.A.E. 50 viscosity MUST be used.

the 'next page' of the 1938 manual states 50 wt must be used when the heavy duty air cleaner is used in place of the standard one .... can anyone identify the difference between the standard and the heavy duty air cleaners for 1938?

OTOH, the 50's manuals specifically call for 50 wt in the 'standard' air cleaner, but in 1955 they call for 20 wt in 'freezing weather' .... is it really going to make much difference? I've always used the same 10-30 in the air cleaner and the 283 in my 58, summer or winter, maybe I'm getting a little 'top end' oiling?

Bill

No telling what kind of 1938 details you are looking for, Bill.

A copper gauze oil-wetted air cleaner is shown and described on page 167. Two types of "oil bath type" air cleaners are referred at the bottom right of page 167, and are described on page 168?

The A-D air cleaners (to the mid-50s) were either oil-wetted (standard) or oil bath, engine oil wetted the standard filter/clear, and 50 weight oil was used in oil bath cleaners (unless below freezing - 20 weight).

I do not know about mid-to-late 50s air cleaners (except for the oil bath cleaner that came on my 1960 261 from a school bus - no PCV on that one, and it looked like earlier oil bath air cleaners).

My local orielly auto carries SAE50 valvoline

...pic...

...pic...

Ok, it calls for 50wt and i'll keep looking. I understand why a light oil might not be so good but the only purpose is to catch dirt so why won't 90 work. i'm just asking.

Here is an explanation on how they work.

In extremely dusty environments, the oil might have to be changed every day.

From the second link:

"Potential Problems

The first problem comes with using the wrong weight oil. Use of oil that is too light will cause the oil to be drawn beyond the filter and into the engine. Use of oil that is too heavy will not allow the oil to be drawn up far enough and much of the air cleaning surface area ends up being unused. Manufacturer owner manuals always show the oil weight that is designed for the system. Engineering of the system (we hope) will have picked just the right weight for the size of the cannister, cup, and vacuum pressure."

I have used this style of filter for many years. Being simple-minded, I just use what was recommended by GM. I do almost no cold-weather driving, so I stick with 50 weight oil.

Good catch Tim. I shudda read a bit farther. Be that as it may I used 30 weight until I decided to go with a dry element and never had an issue with pulling oil through the carb.

A word of advice when searching the internet. E-How, How Stuff Works, Yahoo Answers, WikiHow, Ask.com and all the other so called answer sites are written by yahoos most of the time or people with no idea of what they are taking about. They look up stuff themselves without stating their sources, and then write it plagiaristic style so they look smart and get "points" or payment from the site. Take all those kind of answers with a grain of salt. I rely much more on the experience of the members here that I trust and can communicate with. Not speaking of TC's link, (Yesterdays Tractors I consider a good source) it just made me want to remind all. I never even click on those types, just known car guys, Company websites, scientific studies, Associations or other forums to read all the different opinions not just one answer by some actor.
I looked up all the decals I could find, all GM/AC decals said 50 wt. and many also said 20 wt. winter. Old ford decals said use same as engine oil. I always used same as engine oil back before paper element, That's what my dad did because we didn't have the luxury of running down to Napa. Just had one case of 30 wt. Havoline. Never had any smoke from engine sucking oil, fouled plugs or other signs of splish splash. I like Amsoil type systems now.

The main thing I have seen happen from using to thin of oil is sloshing out onto the engine, and of coarse then blowing back on the firewall.

Yeah, I saw alittle residue down alongside the carb today. I'm running 30w, time to try something thicker.

As I stated before i'll keep searching and find some 50wt oil, but it's just nice to know why. The articles in Tim's post make since. Thanks.

I know the Harley shop carries or carried it. That is what the 1958 Sportster I use to own called for.