bought a Pontiac G8 GT and age-old oil question

[Throckmorton]

BTW, according to that forum link I posted, synthetic oil is much better at high temperatures. My Miata overheated once, and I had to get it towed. The engine seemed fine. Did it get hot enough for synthetic oil to make a difference? I don't know, but it could have been the difference between no damage and catastrophic damage.

 

[LTC8K6]

Did it get hot enough for synthetic oil to make a difference?

Did you drive it for three days with the gauge pegged and the idiot light on?

If not, then probably not.

 

[amdhunter]

woah, another one. We need someone to put up an ATOT garage gallery lol.

On topic: A lot of the guys over at the RX8 Club forums are saying that Mazda will actually try and void your warranty if Synthetic oil is used in my car. Anyone know why that is? I thought synthetic was generally better..?

I am planning to check everything out this weekend as I'll be banging up the car if the weather holds up.

 

[cprince]

woah, another one. We need someone to put up an ATOT garage gallery lol.

On topic: A lot of the guys over at the RX8 Club forums are saying that Mazda will actually try and void your warranty if Synthetic oil is used in my car. Anyone know why that is? I thought synthetic was generally better..?

I am planning to check everything out this weekend as I'll be banging up the car if the weather holds up.

This might be the answer:
http://www.mazdatrix.com/faq/synthetc.htm

 

[amdhunter]

This might be the answer:
http://www.mazdatrix.com/faq/synthetc.htm

:thumbsup:

Thanks for that link. I'll make sure to follow that recommendation from now on. I'll save a few dollars in the process also.

 

[zerocool84]

Why does this always have to turn into an argument??? If the manual calls for synthetic then use it. If it calls for regular dino oil then use that. Follow what the manual says and enjoy a car that will last for many years to come.

 

[WhoBeDaPlaya]

It's not much more expensive with all the annual deals on Mobil 1. Plus the compression ratio in my motor is pretty high (10.55:1), so I just like to treat her as best I can

 

[SJP0tato]

Why does this always have to turn into an argument???

Because it's very difficult to gather empirical evidence that pushes acceptance that one is better than the other, except anecdotal experience.

The best thing I've heard of is go 5k miles, send in your used oil to the oil analysis lab, and see what they say. If they say you're fine, push it to 6k next time. If they say you have excessive wear, go less miles or use a synthetic. Wash rinse repeat.

Or you can rant/swear your "sense" in driving the car is all the evidence you need, and vehemently defend your views.

The 2nd option is much easier (and cheaper) than the first. :-D

 

[Eli]

Here is the bottom line:

Unless you do oil analysis, anything any of us say is a pure guess. It could be an educated guess, but it is still a guess.

The only way to tell if the brand and weight of oil you chose is doing its job under your environmental conditions with your driving habits and your individual engine is to run oil analysis.

Essentially, oil change intervals are worst case scenario numbers, because these variables are impossible to figure in.

You may well be able to get 10,000 miles out of synthetic. You also may well be able to get 10,000 miles out of a high quality regular oil. The distinction between synthetic and dino is actually quite blurred - there are high quality dino oils that have better specifications than low quality synthetics. It's just not black and white.

The thing that people need to realize is that not all brands are created equal. There is a very wide variation in formulation, which may or may not work well for your engine, driving habits and environment.

To complicate matters, a 10W-30 isn't a 10W-30 isn't a 10W-30. The numbers on the bottle actually tell very little about the properties of the oil, it is just a general guideline. There are 0W-30's that are closer to 40 weight, and 5W-30's that are closer to a 20 weight.

It really is very counter intuitive. I suggest if you are really going to worry about this, do some research on BITOG and do oil analysis.

After you get an idea of what is and isn't working for your engine, you don't have to keep doing them. I say you should have a good idea of what brands and weights are good after 5 tests if you do some research to narrow it down in the first place.

Edit: I feel the need to elaborate more.

Most people don't pay any attention to their driving environment. If you live in an area where it is very hot in the summer, and very cold in the winter, you will probably find that synthetic is better just for the convenience factor - that way you're less likely to have to use two grades throughout the year. A car driving in Arizona during the summer demands different oil characteristics than the same car driving in Alaska during any time of the year.

It's silly to make blanket statements on this subject. They are anecdotal at best, and completely wrong at worst. Again, I will reiterate - the only way to know for sure is to do oil analysis.

 

[StageLeft]

I use (used ) Mobil 1 in my Maxima for 100k miles until sold but only Castrol dino in our van. I'd probably just go with what's in the manual unless you are very sure you will keep it for many years. If, to maintain warranty, you have to change the oil often (for example 2010 corolla and prius require each 5k which I am sure is overkill) it would be silly to do syn.

 

[LTC8K6]

Here is the bottom line:

Unless you do oil analysis, anything any of us say is a pure guess. It could be an educated guess, but it is still a guess.

The only way to tell if the brand and weight of oil you chose is doing its job under your environmental conditions with your driving habits and your individual engine is to run oil analysis.

Essentially, oil change intervals are worst case scenario numbers, because these variables are impossible to figure in.

You may well be able to get 10,000 miles out of synthetic. You also may well be able to get 10,000 miles out of a high quality regular oil. The distinction between synthetic and dino is actually quite blurred - there are high quality dino oils that have better specifications than low quality synthetics. It's just not black and white.

The thing that people need to realize is that not all brands are created equal. There is a very wide variation in formulation, which may or may not work well for your engine, driving habits and environment.

To complicate matters, a 10W-30 isn't a 10W-30 isn't a 10W-30. The numbers on the bottle actually tell very little about the properties of the oil, it is just a general guideline. There are 0W-30's that are closer to 40 weight, and 5W-30's that are closer to a 20 weight.

It really is very counter intuitive. I suggest if you are really going to worry about this, do some research on BITOG and do oil analysis.

After you get an idea of what is and isn't working for your engine, you don't have to keep doing them. I say you should have a good idea of what brands and weights are good after 5 tests if you do some research to narrow it down in the first place.

Edit: I feel the need to elaborate more.

Most people don't pay any attention to their driving environment. If you live in an area where it is very hot in the summer, and very cold in the winter, you will probably find that synthetic is better just for the convenience factor - that way you're less likely to have to use two grades throughout the year. A car driving in Arizona during the summer demands different oil characteristics than the same car driving in Alaska during any time of the year.

It's silly to make blanket statements on this subject. They are anecdotal at best, and completely wrong at worst. Again, I will reiterate - the only way to know for sure is to do oil analysis.

That's why you do what it says in the owner's manual. The mfg has already done all the oil testing necessary for a street car driven normally.

 

[Bignate603]

BTW, according to that forum link I posted, synthetic oil is much better at high temperatures. My Miata overheated once, and I had to get it towed. The engine seemed fine. Did it get hot enough for synthetic oil to make a difference? I don't know, but it could have been the difference between no damage and catastrophic damage.

Oil breaking down doesn't happen in a few minutes unless you're literally burning it. It's a function of temperature and time. If you weren't keeping it hot consistently for a long time it won't matter at all.

 

[HarryLui]

Use synthetic, then send the oil in at 5k to see how the oil is holding up.

 

[Throckmorton]

Oil breaking down doesn't happen in a few minutes unless you're literally burning it. It's a function of temperature and time. If you weren't keeping it hot consistently for a long time it won't matter at all.

Yeah but oil thinning out to a water like consistency happens as soon as it gets hot

 

[thescreensavers]

I use (used ) Mobil 1 in my Maxima for 100k miles until sold but only Castrol dino in our van. I'd probably just go with what's in the manual unless you are very sure you will keep it for many years. If, to maintain warranty, you have to change the oil often (for example 2010 corolla and prius require each 5k which I am sure is overkill) it would be silly to do syn.

Used Motor oil wtf lol you could of used Dino oil thats new for like 15 buck?

How much was the Used motor oil any how?

 

[Eli]

That's why you do what it says in the owner's manual. The mfg has already done all the oil testing necessary for a street car driven normally.

No they haven't.

Like I said, the numbers in the manual are worst case scenarios. They have done us a favor by giving "Light", "Normal" and "Severe" duty oil change intervals, but that's about as good as it gets. The problem is they don't give solid, in depth criteria for these labels. Most people would think that a quick 5 minute drive to the store would be "Light" duty, but that couldn't be farther from the truth.

You're ignoring the main point of my tirade. There are too many variables. From Alaska to Arizona, and everything in between. From Grandma, to 16 year old boy with a leadfoot. From flat plains to mountainous terrain. From Mobil 1 to Store brand.

They don't spend the time and money testing [oil] for all of these variables. They just give us worst case scenario baselines to go by. Just because they say an oil should last 5k miles under "Normal" conditions does absolutely not mean that it will - there are too many variables. On the other hand, just because they say an oil will need to be changed at 5k miles under "Normal" conditions does absolutely not mean that it will.

The only way to know for sure is to run oil analysis. Everything else is just a guess - even if it is educated.

 

[IcePickFreak]

BTW, the manual simply states, "Engine oil which meets GM Standard GM6094M and displays the American Petroleum Institute Certified for Gasoline Engines starburst symbol..."

That standard can be found here http://www.gm.com/corporate/responsibility/environment/maintenance/gm_approved_engine_oils.pdf
It's the second half of the list.

That said, I agree with the above if you really want hard evidence run it for 5,000 or so, or wait for the OLM to get down around 30% and then send it in for analysis. It's relatively inexpensive. I've used http://www.blackstone-labs.com/ in the past, they're great to work with. Worst case scenario you learn to move to a different oil based on some real data. Any of the oil on GM's list certainly won't toast your motor with a single 5,000 run through if it doesn't trip the OLM.

 

[LTC8K6]

No they haven't.

Like I said, the numbers in the manual are worst case scenarios. They have done us a favor by giving "Light", "Normal" and "Severe" duty oil change intervals, but that's about as good as it gets. The problem is they don't give solid, in depth criteria for these labels. Most people would think that a quick 5 minute drive to the store would be "Light" duty, but that couldn't be farther from the truth.

You're ignoring the main point of my tirade. There are too many variables. From Alaska to Arizona, and everything in between. From Grandma, to 16 year old boy with a leadfoot. From flat plains to mountainous terrain. From Mobil 1 to Store brand.

They don't spend the time and money testing [oil] for all of these variables. They just give us worst case scenario baselines to go by. Just because they say an oil should last 5k miles under "Normal" conditions does absolutely not mean that it will - there are too many variables. On the other hand, just because they say an oil will need to be changed at 5k miles under "Normal" conditions does absolutely not mean that it will.

The only way to know for sure is to run oil analysis. Everything else is just a guess - even if it is educated.

Cars are tested in all sorts of weather. Engines are too. Oil analysis is done extensively by mfgs. Unless you are racing, or have modded the car, there is no need for oil other than what is recommended.

GM did extensive oil analysis in the development of the OLS system alone to compare change intervals recommended by the OLS vs recommendations by oil analysis.

 

[Fenixgoon]

fwiw, edmunds tested the G8's oil system. they found that when the computer told you it was time to change the oil, it was time to change the oil (i think they went 8-9000miles)

in any event, stick to whatever the owner's manual / MFR recommends. i don't see how you can ever go wrong doing that.

 

[Bignate603]

No they haven't.

Like I said, the numbers in the manual are worst case scenarios. They have done us a favor by giving "Light", "Normal" and "Severe" duty oil change intervals, but that's about as good as it gets. The problem is they don't give solid, in depth criteria for these labels. Most people would think that a quick 5 minute drive to the store would be "Light" duty, but that couldn't be farther from the truth.

You're ignoring the main point of my tirade. There are too many variables. From Alaska to Arizona, and everything in between. From Grandma, to 16 year old boy with a leadfoot. From flat plains to mountainous terrain. From Mobil 1 to Store brand.

They don't spend the time and money testing [oil] for all of these variables. They just give us worst case scenario baselines to go by. Just because they say an oil should last 5k miles under "Normal" conditions does absolutely not mean that it will - there are too many variables. On the other hand, just because they say an oil will need to be changed at 5k miles under "Normal" conditions does absolutely not mean that it will.

The only way to know for sure is to run oil analysis. Everything else is just a guess - even if it is educated.

So the GM's proving grounds in Mesa, Arizona and Kapuskasing, Canada have nothing to do with hot weather and cold weather testing under extreme conditions?

 

[Eli]

So the GM's proving grounds in Mesa, Arizona and Kapuskasing, Canada have nothing to do with hot weather and cold weather testing under extreme conditions?

Fair enough.

What about all the other variables, though?

I will concede that I don't know much about GM's testing, or their OLM. Maybe they really do more than I've been lead to believe.

Perhaps these methods really have gotten better. I still contend that there are too many variables. Weather is only one factor. I would say the oil in use is one of the next biggest factors, and the OLM can't compensate for that.

I would still run analysis just so I know how my individual specific engine is doing under my driving habits and environmental conditions.

 

[CraigRT]

I heard those G8's have a huge sump.. I'd go with conventional. Conventional thesedays is fine. I am using Valvoline convetional in my VQ35 and it seems to run exceptional.

If you feel like switching down the road fine, but running a quality conventional ain't going to hurt a thing.

Mobil clean 5000
Pennzoil conventional
Quaker State
Formula Shell

etc etc

 

[Bignate603]

Fair enough.

What about all the other variables, though?

I will concede that I don't know much about GM's testing, or their OLM. Maybe they really do more than I've been lead to believe.

Perhaps these methods really have gotten better. I still contend that there are too many variables. Weather is only one factor. I would say the oil in use is one of the next biggest factors, and the OLM can't compensate for that.

I would still run analysis just so I know how my individual specific engine is doing under my driving habits and environmental conditions.

They aren't exactly nice to the cars when they're doing the testing. For a truck they'll do hauling and towing right up to their max rated conditions in relatively extreme conditions. For sporty cars they'll drive it hard out in the heat. Hell, I bet even for a minivan they'll load it up to its max vehicle weight and drive it up and down hills. This isn't just to check the oil, they're also looking to see if all the other components of the car and deal with extreme conditions.

 

[slashbinslashbash]

I will concede that I don't know much about GM's testing, or their OLM. Maybe they really do more than I've been lead to believe.

From what I have heard, it at least takes into account how hard the engine has been worked, as well as general weather info (whether it gets this from intake air, coolant temps, oil temps, or whatever, I don't know). If you push an engine to redline regularly, or have a lot of starts in cold weather, the OLM will ding you sooner than if you baby the engine or only drive in a mild climate. Combine that with "easy" stuff like elapsed running time, elapsed real time, and number of miles driven; and you have a fairly sophisticated system.

Also, according to this patent, they also have a system for diesels which can discern changes in engine oil viscosity directly.