Zaavan

Hi everyone, I have a 2007 Lexus ES350. I just got it in February and got an oil change the next day when I bought it. I will do the next one at home. But my main question is that the dealer recommended that I stick to conventional oil. But considering my car has 109k miles. I wanted to switch to full synthetic and high mileage oil. Anyone done this yet or the dealer tell you that conventional is recommended and switch to synthetic or full synthetic? I just wanted to know if I will be fine going to full synthetic. But I'm aware that once I switch I can't go back. Can someone please fill me in on what I should do. Stay with conventional or go to synthetic or full synthetic.

tolian21

Given the age of your car and unknown history of how often oil was changed and if synthetic was used, I would stick with conventional oil to avoid any surprises with leaks. Some people will say that synthetic does not cause a leak, which is true, but if you have crappy seals that are barely holding up, synthetic will wash them and they could leak.

sure you can go back and forth, but better stick with one thing.

tolian21

Btw, all my cars on synthetic oil for past 20yrs which I change myself. But I bought them new, and synthetic went in a first oil change.
old car with unknown oil change history is risk to go synthetic, I would not take this risk. But if you are for some excitement, you can put synthetic and hope you dont develop leaks

Zaavan

Thank you. What is a good brand conventional oil i can use. I've used mobil 1 in the past for other cars, but that was full synthetic.

ESh

Put M1 5W30 EP, Amsoil SS 5W30 with OEM filter.

tolian21

there are many, mobil makes regular oil too. As long as it has the right weight, API certified you should be good. Change it every 5k miles.

Zaavan

I'm in between Castrol Edge and Mobil Super. Any experience with either of them?

tolian21

They are all the same

ESh

Avoid Mobil Super. This engine calls for Mobil 1 5W30 Full synth.

tolian21

This engine does not call for full synthetic. 5w-30 API certified.
Any major brand conventional oil will do fine if he changes every 5K miles. His car is old, and he does not know if it was using synthetic or not. Without knowing anything, the most conservative approach is to use conventional oil and change it at manufacture recommended interval.
We can sit here and argue about synthetic oil not causing a leak or not, will any of us pay his repair bill if he notices a seal leak shortly after putting synthetic?

Zaavan

Now my car was done 6 months ago. And i barely put like 800 miles on it. Should I still get it done in 6 months or wait till I hit 5k miles. Also, I'm just gonna go with conventional Pennzoil or Castrol GTX 5W30.

Wilson2000

I believe conventional oil and synthetic oil of the same weight, will leak at the same rate, regardless of the age or history of oil use. I haven't seen any science that indicates otherwise, I've only heard anecdotes. In the old days, motorists were faced with a similar decision to go from non-detergent to detergent oil, and the threat of engine damage was real. I also believe this real danger is what makes today's motorists believe there is something to the modern myth of synthetic oil being more prone to leaks, or other harm, than conventional.

Project Farm does all kinds of testing, and I recommend his YouTube videos if people care to learn more about motor oils. After seeing his comparative tests of modern synthetics, I've converted from using Mobil 1 to using Penzoil Platinum Plus. I always use premium filters too from Purolator, Wix, K&N, Bosch, etc.

I'm not seeking a debate. I'm simply offering my opinion based on my research and 50+ years of automotive experience doing all my own maintenance and repairs.

Last note: I would not recommend oils or additives, formulated for high-mileage engines, with "seal conditioners" unless one is going for a short-term fix. They chemically soften the seals, but also degrade them.

tolian21

Exactly, if you research this topic on internet, when switch is made to synthetic oil in poorly maintained, old and neglected engines, leaks do happen. Good luck explaining to the customer that it was not the oil, but rather coincidence that engine seal gave up just around the time when switch was made. These are not myths, but observations made by mechanics. The old seal could be barely holding up, maybe it will hold another few years, you put highly detergent synthetic oil, it will wash all the years of abuse, and surprise the seal is bad.
Its easy to give advices on internet when you dont need to pay for repairs.
there is no compelling reason to introduce synthetic into a 13 yr old car since its unknown what oil was used or if it was even changed on time.
If synthetic oil is not required, why bother now?

tolian21

scotty has the same opinion, engineers say its impossible but mechanics see it happen, very unusual coincidence? when it leaks, keep telling yourself “its not the oil”. Good luck.
The bottom line question to ask “why I need it”

Wilson2000

Washes what exactly? What makes you think synthetic oil has more detergent than conventional?
Because it offers superior protection.

Again, not looking for a debate. Mine is just one more opinion to throw on the heap of anecdotal evidence.