Here it is. I have a 2015 Hyundai Accent, 1.6 litre GDI engine with now 100,000 miles on it. Have put 70,000 on it since buying it.
The factory oil weight is the 5W-20 stuff (I believe synthetic is recommended) and the manual says to change every 7,000 miles.
I run 10W-30 conventional oil and change the oil/filter every 3,500-4000 miles. Here in the south the summer temps are 92-100 degrees during the day. I run 80 MPH (2,600 RPM's) on the interstate going to work (about 20 miles of the 32 mile drive) and any time I am on the highway, plus a lot of stop and go. I don't baby the car, but I don't beat on it either. So I use the 30W oil based on the hot summer temps and my driving style. I burn 1 Quart
of conventional oil each 4,000 miles - which I think is fairly good.
Decided to try an experiment. Switched to a synthetic oil this past oil change. I have gone 700 miles so far and I am down 1/3 a Quart
already. I figure I might get 2,000 miles to a quart - 1/2 the oil mileage I get from conventional oil.
So if my oil mileage is what I think it will turn out to be, or less, then that means if I were to change oil based on the manufacturers recommendations, I would have to add 3 1/2 Quarts to reach 7,000 miles. That's a full oil change as it only holds 3.8 Quarts with the filter.
Hmmm. So if I only use 1 Quart of conventional oil in 4,000 miles and would use up 2 Quarts of synthetic oil in 4,000 miles.......which do you think I would recommend?
Now the argument here may be "but your engine will last longer with synthetic oil." Oh yeah, BS. My 1997 Toyota had 271,000 miles on it before I sold it using conventional 10W-30 oil and burned 1 Quart every 1,800 miles. Still pretty darn good oil mileage use at that high of mileage.
So the oil consumption I am seeing right now would indicate to me that conventional oil is better, and the high consumption of synthetic oil is reason for the manual to state an oil change every 7,000 miles because you are constantly adding fresh oil that extends the overall life of the oil in the engine - less oil changes, but you use more oil.
I guess this is to satisfy the "save the planet people," as the manufacturers push the oil change statistics of new cars versus old cars BUT leave out the fact that you use more oil between changes. And that's how you baffle the ignorant with BS rather than facts.
Using my car as an example, I drive a yearly total of about 21,000 miles each year, and based on 1 Qt of conventional oil burned per 4,000 miles versus 2 Qts of synthetic oil burned in the same 4,000 mile period the BS spin goes like this: What they tell you is
that's just 3 synthetic oil changes a year versus 7 conventional oil changes because synthetic oil has an extended life. What they don't tell you is
that you will burn
10.5 Quarts of synthetic oil versus 5.25 Quarts of conventional oil in a years time. Can you see the math or am I doing something wrong in my calculations?
I won't be using synthetic oil anymore, nor will I recommend it to anyone. Next oil/filter change will be conventional 10W-30 again.
That's my personal experience, and opinion on synthetic oil. I do not recommend it on any older engine for sure. If you want to use it, it is your choice.