I'll add that the VR-1 I use is not cheap (about $8/at), I change it every spring.
I'll put 1500-2000 miles a year on my car.
I'll put 1500-2000 miles a year on my car.
FWIW.... Just be aware that a 15W50 full synthetic at cold temps (like below 40F) is going to be as thin as a 5W dino oil at those colder temps. The 'cold' temp viscosity of motor oils is measured at 104F and the oil's behavior at much colder temps can be quite different depending on the oil material. Pout them both out of the bottle at room temp and the lower viscosity of the full synthetic will be immediately obvious.
So a 15Wxx Mobil1 is gonna work OK for most street engines, even at cold temps.
And yes, the old stock spring pressures seem to not be an issue with the now-lower ZDDP levels. From several research articles read, the ZDDP gets 'activated' when pressures on the microscopic 'peaks' gets past a certain level, and the less the spring pressure, the less ZDDP gets used or needed. I personally will try to stick with the older, higher levels regardless.
This maybe correct for you to do so..as in 1000 miles or a yearly oil change. My rule of thumb is 3000 miles or at least yearly. Fresh oil and filter before I tuck it away for its winter slumber.When should the oil be changed? Been changing oil at 1000 miles.
Thanks for the respect LOL, but please read the below link and you will see where the temperatures are set for viscosity testing of engine oils: 40C and 100C. What is getting confused here is the testing specs versus the SAE and ISO published specs for very low temperature grading. Those are 2 different things. And I am not aware of any testing or grading specs at 0 degrees C for engine oils.Sorry, but with all due respect, that's incorrect.
The first number that is the prefix for the "W" is the grade assigned to the oil based on it's flow properties at 0°C, or 32°F, and the second number represents the flow properties at 100°C or 210°F. Or, in other words, the freezing and boiling points of water.
A 15W oil, regardless of it's base stock, will flow in the range specified for it at 0°C, and not out of it. Doing so would mean it is not a 15W, but rather the oil would be assigned the grade number that is defined as that which flows as it actually did.
Thanks for the explanation. I will look into it more and see where I am going wrong on the low temperature testing. I am thinking that the 40/100c testing is for checking viscosity index and that is where I am going off the rails with this. And yes with the lower VI's added to synthetics; that is also as I understand it.Sorry, but with all due respect, that's incorrect.
The first number that is the prefix for the "W" is the grade assigned to the oil based on it's flow properties at 0°C, or 32°F, and the second number represents the flow properties at 100°C or 210°F. Or, in other words, the freezing and boiling points of water.
A 15W oil, regardless of it's base stock, will flow in the range specified for it at 0°C, and not out of it. Doing so would mean it is not a 15W, but rather the oil would be assigned the grade number that is defined as that which flows as it actually did.
Synthetics generally have a higher viscosity index than dino base oils, which means they are more resistant to thinning when heated. That means that less additive, such as viscosity index improver or pour point depressant, can be used to make it perform and stay in spec. When additives are consumed, that's a way we get to the situation Castrol likes to describe as "breakdown."
Your assessment of how ZDDP works, however, is spot on as I understand it.