Before I would go on a job like this I would clarify WHO is paying you, the purchaser of the faulty item or the STORE??
If it is the STORE do they want a report on the said damage before you proceed?? If so this must be paid for by them at least £60.00 for your expert knowledge, also make sure that they agree with YOUR terms of Trading
'CASH ON COMPLETION'.
As regarding the type of oil, I got no idea.
Just trying to say DO NOT WORK FOR NOWT for them!!!