I own an 06 GS300 AWD with approximately 163k miles. Is it safe to switch from conventional oil to full synthetic after 120k miles? Are there any possible consequences? I'm hearing an ugly rumor that switching to synthetic after a certain milestone of mileage that it could be harmful but I'm reading around this neighborhood and I'm hearing the contrary but just want to get some input if anybody has any. I'm not experiencing any problems since I switched to Mobile 1/Royal Purple fully synthetic 43k mi ago. Any feedback or constructive criticism even would be greatly appreciated.

 

Yes, synthetic is better, period. It's simply a higher quality, longer lasting oil that reduces engine wear. Don't listen to rumors and old wives' tales. If it was going to cause any problems, you would have found out long before 43k miles.

 

Synthetic oil is better 100%, but if you tell me you are using conventional oil and running it to 3k miles vs buying high dollar sythetic and running it 5k-up miles then no I would avoid this on the 3GS. Our engines have issues with small oil passages in the pistons, many member have had issues with oil consumption. Once they reach 5k miles they will burn a quart or two. We have seen guys who ran their oils to 10K miles, all while using the same oil filter. Sure the oil will last, but the filter will get clogged, your engines internals will get clogged. It's just not worth it imo

Our engines are low revving, and are not high compression nor do we have turbos, that generate a lot of heat. Honestly it doesnt justify spending the extra money for synthetic. I would stick with conventional oil and keep the oil changes at 3k miles using oem oil filters.

Unless you do a lot of highways and live in a clean climate, and baby the thing I would suggest synth and 5k mile oil changes. But if you are like many of us in a hot climate, with stop n go driving in the city. Then stick to what was working with your car. You will not see anything magical happen when switching oil, other then a hit in your wallet.

Im at 200k miles on a 2008 GS350 AWD, no oil issues! I use castrol synthetic blend with oem filter and I change them every 2,500-3,000 miles. I'm a firm believer in replacing fluids sooner so that things are cleaner and fresher.