Like I have said before, none of my owners manuals have different oil change recommendations for Syn vs dino, and the OLM doesn’t know or care what kind of oil is being used. Same change rates regardless of oil IMHO.
Just how much of oil contamination is due to oil breakdown and how much is due to blowby I don't know. Todays EGR systems are pretty effective at sweeping out blowby.
Sweeping out blow-by? Doesn’t the EGR reintroduce exhaust gas (which is essentially the same as blow by) right back into the combustion process, creating more blow-by?
True. But it further burns it, most of which goes out the exhaust. Only a tiny fraction of it becomes blowby.
Also: True the OLM can’t distinguish what kind of oil is in there. It is based on an integrated set of data by monitoring how the car is driven. I would bet if it could actually monitor the condition of the oil it would be more meaningful.
EGR valves have nothing to do with blowby…That would be the PCV system…
TRUE STORY
I Purchased My Wife’s Former Lease/Rental Car Impala With 10,000 Miles On It, Four Years Ago & Put It In My “Family Fleet” And Began 5,000 Mile Interval Oil Changes, Using Mobil-1 Extended Performance 5w30, Exclusively.
Two years ago, at 60,000 (60,091 to be precise) miles, during an oil change I took a sample of the drain oil and sent it to Blackstone Laboratories. The oil had 4,818 miles on it. It should be noted that the car’s onboard Oil Life Monitor is just about in synch, agreeing with my 5,000 mile intervals, although it doesn’t “know” what kind of oil I use.
Bottom line was, besides all the technical information pertaining specifically to my oil/engine wear, Blackstone ( who provided a personalized paragraph) concluded, “In any case, nothing looks out of line here. This is a nice report at 60,091 miles.”
I can’t say if the results would have been similar had I used conventional (dino) oil, but just throwing in an anecdote to support my 5,000 mile change intervals.
CSA
Oops, I meant to say PCV, not EGR in my post last night. It was 1 A. M. My apologies.
The other thing to consider in favor of synthetic in this never ending debate, is time vs mileage. Regular oil change intervals for non synthetic, at least for my cars, stipulate something like 5k or 6 months to a year. Synthetic oil being more stable maybe a better alternative if you drive a car less then 5k miles in a period more then a year for a seldom used toy for example. Even if you choose to change it every 5 k, you could be better off using synthetic.
It gives you a huge “natural buffer” too if unexpected situations pop up. For example, our car stipulates 10k synthetic oil changes while the truck is 5k non synthetic. If I am at the 4.5k mark on each car and a trip call means I must jump in the car and go a large number of miles, rather then change earlier, take the synthetic car and change at a convenient time…of course, we are taking the car regardless so I hope you get the point otherwise. Being anal about oil changes because the motor may self destruct one mile over the change limit is mitigated…some what.
A reminder too, that every mind set arguing in favor of 5k oil changes were arguing for 3k when the 5k interval was introduced. No doubt, when life time oil changes come in, we just may move up to arguing for 10k intervals. It’s a matter of relativity.
Thanks everyone! I’m going to change my old school thinking (3000 oil & filter w/ dino) to 5000 oil and filter synthetic. Toyota calls for 5000 w/ dino. I drive mostly highway and I’m driving more now, about 2000 a month, and 6 week oil changes are becoming a PIA. Any comments? Rocketman
Sounds like an excellent idea
That would mean 10 week oil changes, correct?
I also recommend tire rotations at every oil change. The car will probably be on a hoist, or at least on jack stands, anyways. Good time to do it. Plus, every time you take off a tire to rotate it, you can take a quick look at your brakes.
@dagosa (& Anybody Wishing To Comment)
Try Sending Oil Sample(s) To Blackstone Laboratories With different variables of oil type (conventional / Synthetic) And Miles Of Use And See What Reports Say. They Will Welcome Any Comments, Questions, Or Special Concerns Customers Bring. I Should Put My Money Where My Mouth Is And Try It, But All My Vehicles Use The Same Oil And Intervals.
I suspect the analyses would totally back-up just about everything you’ve said. I think my program is over-kill, but that’s how I roll.
They’ll send you sample bottles, packaging, labels, instructions, etcetera, for an almost nominal fee.
I guess the type/age/miles of the vehicles would still be a major variable, but results would be most interesting and help calm the debate, maybe. It would be fun, anyhow.
CSA
Here ya @dagosa I normally change at 5000. Had 3000 on the oil and a 3000 mile trip. Rather than change 2000 early, went to 6000 with syn with no problem. I didn’t worry about it. My OLM quickly went from 50 to 40% though the last 1000 miles. (Incidentally your area up there this time of year was beautiful.)
Correction
Oops. Mentioning Blackstone Laboratories I Said, "They’ll send you sample bottles, packaging, labels, instructions, etcetera, for an almost nominal fee.
When I did this a couple years ago, all the stuff I mentioned was sent to me totally free. I meant to say that the analysis itself was for almost a nominal fee, which is paid when you send the sample.
CSA
Thanks again for all of your responses. I was talking to a mechanic buddy and he suggested that I go to 6000 mile with full synthetic (oil & filter) and change the filter in-between at 3000 and top-off with full synthetic. The $$ end of this is almost incidental, dino oil and filter from Wal-Mart now runs me about $20 for a 3000 change while full synthetic and filter will cost me about $30 but will be for 5000 miles. So for say 15,000 miles of oil changes with dino it will cost me $100 for 5 oil changes and for 15,000 miles of full synthetic it will cost me $90 for 3 oil changes. Not enough to worry about. My complaint is the frequency of a 3000 mile change is becoming a pain since I’m driving more now with my job. I think that I’m going with full synthetic and filter @5000. Rocketman
Changing the filter at 3000 miles would be a waste.
I do (conventional) oil changes at 5000 miles and change the oil filter every 10,000 miles.
Yeah! I think changing the filter every 3000 miles would be overkill.
You’ve already got all the equipment out, so there’s virtually no extra time involved in changing the filter, and a new one costs ~$4…may as well do the whole job and change it. Even if the filter is still good, leaving it alone means leaving up to a pint of dirty oil behind.
What rocketman is saying is he wants to change only the oil filter midway between his oil changes. In other words he would change his filter twice as often as his oil.
Going to all that work to get the pan out, jack the car up, etc. to pull the filter and not the plug for the oil seems silly. You can do an oil change in 20 minutes and probably 15 for just the filter and topping off. Seems very unusual advice, plus I’m not a fan of extending oil changes just because you use synthetic. Even though that’s how they used to and some still do market it.
I remember long ago when Mobil1 first came out they claimed it was good for 25,000 miles. Then they lowered it to 15,000 miles. It was then that it was common practice to change the filter twice as often as the oil.
If rocketman is going to change his oil every 6,000 miles then I would say one oil filter per oil change is perfectly adequate.
If you want real synthetic oil, make sure it’s PAO and not type III which is still dino oil. Stupid law makers makes it bad for us folks.