Air compressor oil sight glasses are crucial components to allow you to check the oil level inside of an air compressor. This article will provide you with all the relevant information about them, as well as provide you with products readily available on Amazon.

Table of Contents

What is an Air Compressor Oil Sight Glass?

Most air compressors will have an oil sight glass similar to the one in the image below that make it very easy to check the oil level inside the compressor.

The oil sight glass for air compressor tends to be made of stainless steel or aluminium alloy that screws into the base of the pump or on the compressor sump tank, with a glass window to allow you to see inside it.

How to Use an Oil Sight Glass

The compressor oil level sight glass window will contain a circular mark at the middle of (usually red) which will help you depict the level as it has upper (upper edge of circular mark) and lower limits (lower edge of circular mark).

Typical Air Compressor Oil Sight Glass

You should always aim for the oil to sit roughly half way up the red dot or fall half way between its upper and lower markings.

It’s possible that the sight glass doesn’t have the circular mark in the centre. If this is the case, you should ensure that the oil level is between 1/3 and 2/3 of the vertical height of the sight glass.

My Compressor Doesn’t Have an Oil Sight Glass?

It’s possible that your air compressor doesn’t have a sight glass, not all oiled air compressors do. In this case you would look to use the dipstick to check the oil level.

However, it’s also possible that your air compressor doesn’t have an oil sight glass or a dipstick – but this doesn’t mean it is an oilless compressor!

You would just have to check the oil in a different manner, by draining it into a reservoir and gauging the level that way!

Oil Sight Glasses Readily Available on Amazon

I have found the 5 following oil sight glasses that are readily available on Amazon and all boast great reviews.

Prices pulled from the Amazon Product Advertising API on:

FAQs (Frequently Asked Questions)

How much oil do I put in an air compressor without sight glass?

If your air compressor does not have a sight glass then you should judge the amount of oil being put into the air compressor by using the dipstick. This will have markings on it which will allow you to control the level to the desired amount.

Where is the oil sight glass on an air compressor?

Oil sight glasses can be located on the base of the compressor pump or on the compressor sump tank. Depending on the make and manufacturer of the compressor, this will vary!


If you have any questions regarding the air compressor oil sight glass then please leave a comment below with a photo if applicable so that someone can help you!