Synthetic Oil

[f5fstop]

Good article, but missing some facts.
Many of the additives used in modern dyno oils over the past few years are a lot better than used in the past; thus, the modern "Starburst" symbol dyno oil last longer and is more stable than oil used even five years ago. Unless the engine is of a race design, or has limited airflow to help cool it, dyno oil is all that is required. GM (and all other manufacturers) recommend the oils that they test the engines with during development.

Synthetic will not harm the engine, but in many cases, it is not necessary. Extreme hot conditions and extreme cold conditions will see some benefit, but then again, the GM oil life system, which monitors temps at startup and during engine run, will take this into consideration. Therefore, those who live in AZ will see their oil life percentage decrease faster than those living in MI during the summer. Same holds true to those up in Alaska. Those living in moderate temp areas, with four seasons, will also notice that during the summer their oil life percentage will not decrease as fast as during a cold winter.

You will also notice a difference with your driving habits. Change the oil and go cross country and your oil life percentage will drop slowly. Change your oil and make a hundred one-mile trips to Kroger a mile away, and your oil life percentage will decrease faster.

In addition, there are two primary type of synthetics; Group IV synthetics are made with PAOs, group III are highly refined dyno oil via a process called Hydro-cracking, that is labeled synthetic oil, and is legal to do so. (Mobil sued to have the name synthetic removed from Group III oils back in the late 90's and lost.) Hydro-cracking is less expensive than using PAOs. To be honest, the inroads in the development of Group III oil have made them almost as good as Group IV. There was supposed to be a Group III+ category, but not sure if it has been released.

Last tests I saw showed that only two oils were group IV:
Mobil 1
Amsoil ASL

All other major oils, advertised as synthetic were Group III:
Castrol
Shell
Pennzoil
Valvoline
Havoline
Quaker

It costs a lot less to manufacture Group III synthetics, but as we all know, they charge about the same as Group IV.

Now, to add confusion, there is a Group V synthetic oil based on Esters, and is used by Redline. The only true benefit of Group V is that it's high heat capabilities are superior to Group III and Group IV. A normal car/truck engine will not benefit by the use of Esters, but it certainly won't hurt. Air cooled and Jet engines benefit greatly with a Group V oil.

Another type of oil that is the "blend." When you mix a synthetic with a dyno oil, the oil takes on the characteristics of the lowest group type used. Therefore, a blend oil is basically worthless. If you are considering a blend, you might as well save your money and go with a dyno or pay more and go with a synthetic.

Most important factor, is always use the recommended spec, or a spec that exceeds the spec for your engine. This is important on systems using oil life monitoring systems. The system algorithms are developed knowing the rate of decline of the oil approved with that spec. Using an oil without that spec would make the system inaccurate. So, the oil life indicator might indicate 50%, but the oil is really degraded to around 30%. Using an oil with a greater spec (synthetic), would also make the oil life monitoring system inaccurate, but won't harm the engine. With an oil that exceeds the spec, the oil life system may show a percentage of 50%, but the oil life is actually at around 70%.

[DURAMAX TIM]

Originally Posted by f5fstop

Last tests I saw showed that only two oils were group IV:
Mobil 1
Amsoil ASL

All other major oils, advertised as synthetic were Group III:
Castrol
Shell
Pennzoil
Valvoline
Havoline
Quaker

OK f5, I use a lot of Schaeffer's oils and grease.

looks like they are a mix of both.

http://www.schaefferoil.com/

[Wisha Haddan H3]

As I understand it, synthetic oil doesn't cause leaks, it just finds them. Probably what happened is you already had a leaky or cracked gasket, but it was plugged with sludge. The synthetic oil just cleaned it out. Of course, now it'll leak until you fix the gasket.

[marin8703]

Originally Posted by Wisha Haddan H3

As I understand it, synthetic oil doesn't cause leaks, it just finds them. Probably what happened is you already had a leaky or cracked gasket, but it was plugged with sludge. The synthetic oil just cleaned it out. Of course, now it'll leak until you fix the gasket.

thanks, gotta get on that.

[Agriv8r]

thanx for the info...

[algy]

Good read...

I am always baffled at my OnStar oil life report that reads that my oil has 58% remaining when I've exceeded 4K miles. The dealer wants you in at 3K miles and with synthetics OnStar believes that 8K miles you should change your oil. I have been going in every 4.5K miles.

Originally Posted by algy

Good read...

The dealer wants you in at 3K miles and with synthetics OnStar believes that 8K miles you should change your oil. I have been going in every 4.5K miles.

Attachment 41281

Ignore the dealer on this topic. Why the frequent oil changes at 4.5K?

[f5fstop]

Originally Posted by DURAMAX TIM

OK f5, I use a lot of Schaeffer's oils and grease.

looks like they are a mix of both.

http://www.schaefferoil.com/

I have heard of them, but I don't have any experience or test information on their product. They say they meet the GM spec for synthetic, so it is probably as good as any other syn oil.