Probably because they can make a heavier grade oil into a 10w-30 from group II stocks without using too much viscosity modifier. For the 5w-30 grade they probably need to add some more thermally stable Group III base stocks to get the viscosity index needed.
Probably because they can make a heavier grade oil into a 10w-30 from group II stocks without using too much viscosity modifier. For the 5w-30 grade they probably need to add some more thermally stable Group III base stocks to get the viscosity index needed.
That's one of the reasons why I use 5w30 HM blend instead of 10w30 HM conventional. I assume the 5w30 HM blend has better based oils, plus likely less wear at cold start.
I used 5w30 Maxlife Syn for a decade. It leaked a small puddle on concrete after each drive.
I switched to 5w30 Maxlife Blend (red bottle). Then it leaked only a few drops after each drive.
Then I had my valve cover gasket replaced. No more leak.
My car isn't an oil burner and only had a minor leak using Maxlife 5w30 HM blend (red bottle). Leak now fixed completely be replacing valve cover gasket.
If my car was an oil burner or a severe leaker, then I'd use a 10w30 HM conventional oil. Likely Pennzoil or Quaker State. Maybe Valvoline. And thicker the better (within grade) @ KV100.
As a last resort, I'd go up a grade in a HM oil. Ideally a conventional. 2nd choice a blend.
The spec sheet shows that 20w-50 has a viscosity index of just 126 so it is likely to be all or mostly all Group II or Group II+ base stocks. If there is any Group III included it will be a small fraction of the total.
The only Chevron oil I've seen in last 20 years said ISOSYN on the bottle, which an Oreilly store manager told me is Chevron's brand trademark name for synthetic blend. Am I missing something?
There’s a few other companies that still make conventional oil like Castrol, Chevron, Shell, and Valvoline to name a few. It’s becoming harder and harder to find.
Does Chevron still offer conventional? If it says ISOSYN on the bottle that means it's a synblend, at least according to the manager at my local Oreillys.
Does Chevron still offer conventional? If it says ISOSYN on the bottle that means it's a synblend, at least according to the manager at my local Oreillys.
ISOSYN is mostly just a branding name, but Chevron ISOSYN products typically use Chevron base stocks that are refined to a level in between Group II and Group III so are usually referred to as Group II+. Usually, the term "semi-synthetic" means that some percentage of the base stocks used in an oil are Group III. If a bottle of Chevron oil says "semi-synthetic" on the label, you can be pretty sure it does have some Group III in it. If it doesn't say semi-synthetic but is labeled as ISOSYN, then some or all of the base stocks used will be Group II+.
In most cases, in order for a 0w-20 to 5w-30 oil to meet SP or SQ API standards, it will typically have some Group III oil in it, BTW. It's commonly speculated that just about all SP rated oils conventional in those viscosity ranges have some fraction of Group III base stocks in them.
I didn't think any company still offered conventional motor oil, but fun fact.. Tonight I noticed on Pennzoil website that Pennzoil still offers a conventional oil in a few viscosities.