I still have one overarching question.

I just switched to Mobil 1 10w-30 synthetic oil from regular Quaker State 10w-30 dino oil. I've read multiple posts on the forum relating to this topic but I'm still wondering what would be a good interval to now change my new oil?

I'm thinking 9,000-10,000 miles would be good instead of 3,000. I do mainly highway driving, and I have the 3800 series II with 78k miles on it.

You opinions would be helpful!

 

I may be over doing it, but I use synthetic and change it every 5K miles.

 

I still try to get mine done every 3500 miles or so. But at the same time i have some fudge room there to.

And i dont feel near as bad if im not on the exact mile for this.

i might be doing it as over kill but the price of the oil is cheap in comparison to the price of the motor.

 

I was talking to my son about switching to synthetic (he runs synthetic in his ricemobile, don't tell him Icalled itthat, LOL). He said if it's had regular oil ran through it for as many miles as mine has (110k now, had 108K when I got it two months ago), that it could cause leaks. He said something about the regular oil leaves deposits behindin the seals and gaskets, and the synthetic will "wash" them away, eventually leading to leaks. That's what he was taught in school anyway. Anyone here know anything about that? Any truth to it?
He told me to use Castrol GTX in mine. Have an oil change coming up in less than 1K, so I have to decide soon.

 

Your son is correct, but the reason is synthetic oil has smaller molecules and will find a place to leak, Cars with 100K already have a place to leak normally. Castrol GTX is a good oil and you wont have any problem with it if you change it every 3K-5K.

Roodman03SS, while synthetic oil is far superior oil you still have to contend with dirt so changing atleast the filter every 3-5K is the least you can do, But there is no doubt in my mind that synthetic oil will lube your engine up to 10K no problem.

 

The Previous Owner of my Monte used Mobil-1 in it exclusively. He said he'd go to places that offered Oil Change Deals and bring his own oil in with him and ask them to use what he brought instead of whatever they'd use and charge him the full price for the Oil Change. There were papers showing he changed the Mobil-1 at 75 Hundred -to- 8-Thousand mile intervals.

Since the Engine seems to be running quite well and the Plug Read looked just perfect ... I'm going to start Changing the Oil at 5,000 Mile intervals or less ... maybe 4,000 ... Oil and Filter.

When I do ... what do I do with the "Oil Life Monitoring" Feataure that can be accessed and set by pressing a few buttons on the elaborate Radio System. Do you get to select the Milage that you want to be reminded at ... or does the Computer have a sensor that's tripped by the Oils P-H ... what is it? Pressure related; possibly?

 

not sure about the oil system monitoring.... but as for changing the oil, it all depends on the motor condition... basicly i would check the oil at 3,000 and if it looks clean then check every 1k or so... the main factor on oil live when dealing with synthetic is the filter. the filter will wear out before the oil ever degrades... and if the filter isnt pulling the deposits out... then you have a prob.

the discription on how the synthetic works is dead on. and its not that the synthetic is really smaller, but that dino oil is a mix of diff sizes... say your want siz B oil synthetic will all be B size particals where dino will be mostly B but has A size and C size mixed in. so there will be some much smaller and some much larger... it is these larger ones along with deposits that atack the seals and form acumulation in the motor.

personally i use castrol syntec 5-30 and change about 4 k i usedto do the take the oil thing to someone and even did the walmart upgrade to synthetic... but using their crapy oil filters hurt the life of the oil... right now i use a AC delco fliter and havent had issues.

 

06MC, I see that Castrol makes a high milage oil. Would that be the better one to use?
Thanks for the info.

 

GM just removed Castrol GTX from their approved oil list.
Please see my post I just did concerning the ONLY 6 synthetic oils approved by GM. I've been changing my oil every 12,000 miles on the Mobil 1 extended performance oil, and changing the filter every 6,000 miles with a tire rotattion. But because of my new findings, I'm switching to regular Mobil 1 5w30, and changing it every 5-6,000 miles, depending on what the DIC says my oil life is.
My Solstice GXP owners manual recommends changing the oil per DIC, or every 5,000 miles, along with a tire rotation.

 

Wow, thanks guys for the info!

Judging from your responses I've decided that I will change the oil every 9k miles, and change the filter at 4,500 miles just to be safe. I think I've also convinced my dad to switch to synthetic in his MC so we now have two more converts roaming around the streets lol