We just purchased a house with gloss oil based paint on the exterior. It needs to be repainted. Can I just paint latex over the “good” spots or do I need to prime the entire house first?
Latex directly over oil or alkyd finish is always a no-no. Over a gloss oil is the biggest no-no.
You probably knew that in your heart but were hoping for someone to give you a miracle cure. None exists no matter what Home Depot is willing to advertise.
Prime and finish is your best answer.
Porter Paint Permanizer is a latex formulated to cover oil and convert to latex. Its also a high build product that will help smooth alligatoring. This paint has a lot of binders in it which allow it to adhere to oil. The only negative is you get what you pay for and its very pricey. Its still cheaper than priming everything though!