Dear Peter, Diethyl ether is considered as a non-polar solvent due to its low dielectric constant.

Regards

Peter, Diethyl ether is a solvent with very low polarity (non-polar). It is an excellent solvent for lipids, resins and mineral fats.

In addition other solvents of this type are: chloroform, benzene, toluene, xylene, ketones, hexane, cyclohexane and carbon tetrachloride. A special case is fluorinated solvents, which are more non-polar than conventional organic solvents.

Di ethyl ether is a non- polar solvent for its low dielectric constant.

No doubt, ether and petroleum ether are non polar solvents

Ethyl ethers are Non-polar solvent and can extract polar molecules such as fatty acids

Dear Peter

Diethyl ether has a very low dielectric constant (4.33), it's dipolar moment is 1.3 it's slightly polaire .

So it is considered as non polar solvent.