Normally there's a bit of a trade-off in foundations for oily skin - you can have a mattifying, long-lasting base, but in return you must have heavy coverage, whether you want it or not.
But, If you're lucky enough to have a reasonably even skin tone, Rimmel Lasting Finish will lightly cover redness and blemishes without looking at all mask-like, yet it also lasts surprisingly well, absorbing oil and covering pores for the best part of a day.
The 25 hour claim might be pushing it a bit, but for such a bargain price, you won't find a heat and transfer-proof base better than this.