So I know I'm going to get a variety of mixed responses here, but for my own sanity I need to ask: I drive a 2007 Nissan Xterra with 46k miles, and since the first oil change I've been running synthetic with 5k OCI. I changed over to Amsoil Synthetic at 40,700 and was going to try to extend the OCI upwards of 10k. Regardless, due to some faulty repair work the X has been to the dealership four times since the oil change to replace the oil cooler, front cover and to diagnose a troublesome leak traced to the oil pressure sensor. During these repairs, the service report stated that they refilled the oil on all occasions. I was hoping to order a UOA around 7500 miles, but I'm concerned that the oil is shot. I'm left with the options of paying someone to change the oil and running the risk of faulty service again, or wait until I can change the oil myself (not often since I live in an apartment complex ). My preference is to change it myself as I want to stick with Amsoil Synthetic, but can I risk waiting? Thoughts?