I have firsthand reasonable proof, at least in one regard, even after only 1000 miles new oils of the same rating and grade don't perform the same.
The vehicle is a 1987 Mazda B2200. ‘87 was the first year for the 2.2 liter version of that engine, and it has some well known valvetrain problems. Mine started making a very loud TAP TAP TAP noise from just one hydraulic lifter.
The first interesting thing is it only made noise after it had been driven hard enough and long enough to get the oil really hot which usually required an extended freeway drive. Running errands for hours in town usually wouldn’t show the problem (or it would at least be much quieter).
The second interesting thing is I changed the oil, and the noise stopped completely even after extended freeway driving. But after a month it was back. I’d been running the factory recommended 10W-30 oil and had always used Chevron Supreme in cheap cases of 12 from Costco.
That sure made it seem my one month old API “sunburst” SM rated oil was already losing viscosity when hot compared to a month earlier? This is after only about 1000 miles on the oil.
So, after just a month, and 1000 miles, I switched to 10W-40 Castrol synthetic blend and the noisy lifter stayed quiet for about 2 months and 2000 miles this time but was eventually ticking loudly again after every freeway drive—and this despite one weight heavier on the hot end!
So another change, this time to 20W-50 Castrol blend. And same thing. After about 2000 miles it’s ticking loudly again.
At this point I’m thinking the lifter was probably just getting worse and likely hopeless. A friend who races suggested I try Redline full synthetic 10W-40. Guess what, no noise for 5 months and 5000 miles this time (my normal change interval) and this despite my backing off to 10W-40 (it was winter and I was worried about start up problems with 20-50)!
The above demonstrated to me all the guys (even Blackstone) claiming if you change your oil every 3000 miles, there’s no real difference in oil performance among SL/SM oils once the engine is up to operating temp might not be entirely correct. I can’t speak to bearing wear, but keeping a hydraulic lifter with sloppy tolerance working correctly seems to require a certain viscosity. And 3 different oils failed after only 1000 – 2000 miles where Redline full synthetic worked for 5000+ miles. We’re not talking some high-strung 400 HP 7000 rpm wonder. It’s an 85 HP low-tech four banger in a small light pickup.
It might be Mobil 1 or Pennzoil Platinum would have worked just as well. And, eventually, I had to replace the lifters even running Redline, but do mineral-based oils and blends really start to lose some of their hot viscosity after only a few thousand miles? I’m guessing what’s at fault here are the “viscosity improvers” they add? Perhaps they work better in bearings than in lifters?
Even Blackstone’s “TBN” doesn’t measure the actual amount and health of the Viscosity Improvers. But you’d think their hot viscosity test would show the kind of degradation I experienced?
The vehicle is a 1987 Mazda B2200. ‘87 was the first year for the 2.2 liter version of that engine, and it has some well known valvetrain problems. Mine started making a very loud TAP TAP TAP noise from just one hydraulic lifter.
The first interesting thing is it only made noise after it had been driven hard enough and long enough to get the oil really hot which usually required an extended freeway drive. Running errands for hours in town usually wouldn’t show the problem (or it would at least be much quieter).
The second interesting thing is I changed the oil, and the noise stopped completely even after extended freeway driving. But after a month it was back. I’d been running the factory recommended 10W-30 oil and had always used Chevron Supreme in cheap cases of 12 from Costco.
That sure made it seem my one month old API “sunburst” SM rated oil was already losing viscosity when hot compared to a month earlier? This is after only about 1000 miles on the oil.
So, after just a month, and 1000 miles, I switched to 10W-40 Castrol synthetic blend and the noisy lifter stayed quiet for about 2 months and 2000 miles this time but was eventually ticking loudly again after every freeway drive—and this despite one weight heavier on the hot end!
So another change, this time to 20W-50 Castrol blend. And same thing. After about 2000 miles it’s ticking loudly again.
At this point I’m thinking the lifter was probably just getting worse and likely hopeless. A friend who races suggested I try Redline full synthetic 10W-40. Guess what, no noise for 5 months and 5000 miles this time (my normal change interval) and this despite my backing off to 10W-40 (it was winter and I was worried about start up problems with 20-50)!
The above demonstrated to me all the guys (even Blackstone) claiming if you change your oil every 3000 miles, there’s no real difference in oil performance among SL/SM oils once the engine is up to operating temp might not be entirely correct. I can’t speak to bearing wear, but keeping a hydraulic lifter with sloppy tolerance working correctly seems to require a certain viscosity. And 3 different oils failed after only 1000 – 2000 miles where Redline full synthetic worked for 5000+ miles. We’re not talking some high-strung 400 HP 7000 rpm wonder. It’s an 85 HP low-tech four banger in a small light pickup.
It might be Mobil 1 or Pennzoil Platinum would have worked just as well. And, eventually, I had to replace the lifters even running Redline, but do mineral-based oils and blends really start to lose some of their hot viscosity after only a few thousand miles? I’m guessing what’s at fault here are the “viscosity improvers” they add? Perhaps they work better in bearings than in lifters?
Even Blackstone’s “TBN” doesn’t measure the actual amount and health of the Viscosity Improvers. But you’d think their hot viscosity test would show the kind of degradation I experienced?
