The standard Trico bulb constant level oiler does not have a sight glass on it. If you want to be able to verify the level of the oil and the condition of the oil, at a glance, you need to add a sight glass. There are other types of oilers (Oil-Rite, Watch-Dog) that have a built in sight glass as part of the oiler. Even with these, there is one potential problem. If the pipe between the oiler and the housing were to plug up or freeze, you would be looking at a false level. Another sight glass directly on the housing is a good idea. I would prefer to have both if I was going to specify an oiler.

We are considering phasing out the use of oilers, altogether. This will allow us to seal the housings up air tight and extend oil change intervals. But, in either case, I need a good sight glass on the housing. We have been looking at a 3-D sight glass that threads onto the standard 3/4" NPT connection. This looks very promising and provides better visibility than the old bulls-eye.

Johnny Pellin

I'm pretty sure jp has many times more experience with oilers than me. my reaction was the opposite of his, so i wanted to explore those differences.

> If the pipe between the oiler and the housing were to plug up or freeze

Have you ever seen that happen? was it an exceedingly long pipe? (could be cut back). in theory the opening to a sight glass could get plugged also.

I can see that eliminating oilers allows you to seal the vent. but you still have potential air interchange and oil loss at the seals.

if the seals still vent, there doesn't seem to be a basis to cut back oil changes. maybe it is just a matter of degree of air interchange?

the sightglass does not fulfill the function of making up for oil loss at the seals...you may end up having to monitor level more often to avoid unpleasant surprise of oil dropped below the narrow acceptable range for rolling element bearing while you weren't watching.

both oiler and sight glass is a Cadillac (as long as the oiler isn't hanging out on a long pipe causing potential problems). if I was limited to one I'd prefer the oiler with built in level indicator .

I'm interested in your perspective if I have said something that sounds off base.

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(2B)+(2B)' ?

Also consider the newer Trico Watchdog oilers with integrated sight glass. They are a sealed unit unlike the older traditional Trico oilers. This means they can be used in a semi-sealed bearing housing without spilling oil all over. I don't really see the need for more than this.

I can probably recall perhaps 5 or 6 times when the line to the oiler was plugged or frozen and prevented it from adding oil. I can think of dozens of times when the oiler just malfunctioned and did not deliver oil. If all I had was the old fashioned bulb oiler with no sight glass, the machine would run to destruction. So, I agree, the base case is a constant level oiler with a built in level glass. But, most of our bearing housings were built to include a bull-eye sight glass screwed directly into the housing. If it is there, I would leave it. If it is not there, I would add one. It probably costs less than $10US. I will pay that for a back-up that I probably won't need.

When we talk about sealing up a bearing housing, we are talking about making it air tight. The seals are contacting face seals, the oiler is removed. We add an expansion chamber on the top to accommodate changes in temperature and air pressure with less chance of air being drawn in. In combination with a full synthetic oil this can drastically reduce the introduction of contaminants. We have plants within our company that have gone to 3 year oil changes with very good success. If no oil leaks, there is no need to add oil. If the housing is air tight, the oil will last a very long time.

Johnny Pellin