If what you want is a quotation or offer, then sending a letter of intent makes you look ignorant while requesting a quotation will generally at least make you look like you know what it is that you want. And what you want, after all, is a price quote. Hence you want to request a price quote, via a request for quotation.
SUMMARY _ Put very simply, as a legal or even business document, it's hard to image any document that could be as beset with so many near_crippling legal flaws, traps and pitfalls for its signer, as the LOI. Consequently, it comes as no surprise that in the REAL world of international buying and selling of crude oil, while the crude sellers and their army of sales_obsessed aggressive brokers and agents may generally be infatuated with the idea of having the LOI document widely and routinely used by prospective crude buyers to initiate their purchasing offers, nothing, on the other hand, could be more disliked, more unacceptable or unwanted by most crude buyers, particularly the more credible and substantive lot. What is more, on top of everything else of decisively negative nature about this document, the LOI is a document adjudged by virtually every legal expert in the field as a document that is legally meaningless, worthless, unenforceable and non_binding both on the signatory parties or on anyone, but yet has the potential to bring forth immense and unanticipated legal complications and problems for the signer(s).