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I've just had the diff oil in my 2001 Subaru Legacy Lancaster VDC changed at the AA centre. They have put LS90 in, which I presume is Limited slip oil. I don't think my car has LSD. Is there any possible harm that can occurr.

John

From the "Ask Jack" archives - 14 December 2009

There is a possibility the Legacy has a Limited Slip Differential (LSD), as several Legacy variants did.

Correct me if I'm wrong, but the Lancaster is a used import model. If this is the case, it could be difficult to find a specific oil listing for this vehicle's differential.

LS90 will be a Limited Slip (LS) differential oil, with 90 being it's viscosity rating. It is fine to use a LSD oil in a conventional differential, but not the other way round.

The difference is LSD oil contains a friction modifying agent to lock up the clutch packs inside an LSD, it's lubrication properties are the same however. No harm will occur from this.