Will a syn blend cause the problems a full syn will on an old conv only engine?

Messages
39
Location
MI
Just came from Napa and noticed that GTX 5W30 bottle looks and costs the same as a conventional but is now labeled a synthetic blend. After reading some posts here and asking the Napa guy it seems that most if not all 5W 30 oil is now, or for several years now, a synthetic blend. Most people agree that switching a 300,000 engine that has only seen conventional to full synthetic has a good chance of introducing new oil leaks. Is there a chance that using the new blend standard will have the same problems that a full synthetic could have? Is it better to go up to the 10W 30 that is still labeled conventional? Is all this blend no blend labeling just marketing/legal issues where the oil inside is still the same? Since the blend bottle looks and costs the same as their conventional I am thinking it is made by the same processes.
 
Messages
107
Location
Kansas City
Most "conventionals" are moving to be synthetic blends because it's hard for non-synthetic oil to meet the ever-tightening oil standards. Your last couple oil changes since API SN Plus came out in 2017 were most likely syn blend conventionals.

You're not going to see any "new" problems start, but you could see "old" problems (previously covered up by sludge) getting revealed by synthetic oil doing a better job at cleaning up shop.

If you are breaking in a new flat tappet cam, you'll want to avoid most off-the-shelf synthetics for break-in because they won't have enough zinc, and you'll ruin your new cam immediately. Otherwise, you won't have any issues switching back and forth.
 
Messages
3,664
Location
St. Charles County, Missouri
As referenced above. It's all pretty much syn blend. If you relabel like Valvoline did with VWB, (and I assume NAPA) you get people complaining that it's not real on Amazon. If you continue to label conventional as SuperTech does, it makes little difference cause it's still roughly half group III to meet spec. I guess there's some 10w30 that's still conventional.
 

BlueOvalFitter

Site Donor 2021
Messages
9,494
Location
Cajun Country, La.
Just came from Napa and noticed that GTX 5W30 bottle looks and costs the same as a conventional but is now labeled a synthetic blend. After reading some posts here and asking the Napa guy it seems that most if not all 5W 30 oil is now, or for several years now, a synthetic blend. Most people agree that switching a 300,000 engine that has only seen conventional to full synthetic has a good chance of introducing new oil leaks. Is there a chance that using the new blend standard will have the same problems that a full synthetic could have? Is it better to go up to the 10W 30 that is still labeled conventional? Is all this blend no blend labeling just marketing/legal issues where the oil inside is still the same? Since the blend bottle looks and costs the same as their conventional I am thinking it is made by the same processes.
Myth #3: Synthetic engine oils can wear down seals in an engine and cause leaks. ... In fact, if your seals and gaskets are in good condition, synthetic oil will not leak in your engine. Synthetic oil has not been shown to deteriorate engine seals or gaskets. But it might find an existing leak.

 

BrianApp

Thread starter
Messages
39
Location
MI
I get that synthetic oil doesn't cause oil leaks but if leaks start after switching to it who cares why. My car has several drips so it is not a totally clean machine but if major leaks start after switching I don't care if it is because it does a better job cleaning. I now have leaks I didn't have before and wouldn't have if I hadn't switched. I am not saying that will happen, just that that is the logical argument. Just like Obama said you can keep your health plan and doctor. Sure he didn't eliminate doctors but he made it so expensive for them many had to retire early. End result is still the same. Doctor no longer available or major leaks started when neither had to happen or would have without the change.
 
Messages
4,632
Location
Decatur AL USA
As stated you were already using a synblend and you didn't know it. It's not worth worrying about. If GTX is what has worked for you in the past no need to change unless your looking for a lower priced product.
 
Messages
64
Location
USA
Most people agree that switching a 300,000 engine that has only seen conventional to full synthetic has a good chance of introducing new oil leaks.

Most people agree to that?

Some legends never die. This was an issue way back in the mid 1970s, when the first synthetic group IV oils were introduced. These first generation synthetics were almost pure PAOs, which caused elastomeric seals to shrink. This was addressed 40+ years ago when they learned to add some POE content to maintain seal condition. And it isn't a problem at all on modern group III oils.

However, if you've got an engine with 300k miles on it, obviously whatever you're doing seems to be working so I'm wondering why would would want to change it.
 
Messages
648
Location
Chicago Suburbs
Just came from Napa and noticed that GTX 5W30 bottle looks and costs the same as a conventional but is now labeled a synthetic blend. After reading some posts here and asking the Napa guy it seems that most if not all 5W 30 oil is now, or for several years now, a synthetic blend. Most people agree that switching a 300,000 engine that has only seen conventional to full synthetic has a good chance of introducing new oil leaks. Is there a chance that using the new blend standard will have the same problems that a full synthetic could have? Is it better to go up to the 10W 30 that is still labeled conventional? Is all this blend no blend labeling just marketing/legal issues where the oil inside is still the same? Since the blend bottle looks and costs the same as their conventional I am thinking it is made by the same processes.
your in Michigan ,,Menards has plenty of Conventional oils
 
Messages
2,490
Location
Americus, GA
Just came from Napa and noticed that GTX 5W30 bottle looks and costs the same as a conventional but is now labeled a synthetic blend. After reading some posts here and asking the Napa guy it seems that most if not all 5W 30 oil is now, or for several years now, a synthetic blend. Most people agree that switching a 300,000 engine that has only seen conventional to full synthetic has a good chance of introducing new oil leaks. Is there a chance that using the new blend standard will have the same problems that a full synthetic could have? Is it better to go up to the 10W 30 that is still labeled conventional? Is all this blend no blend labeling just marketing/legal issues where the oil inside is still the same? Since the blend bottle looks and costs the same as their conventional I am thinking it is made by the same processes.
If I had something with 300,000, I would be glad it made it that far. I wouldn’t blink at using a synthetic blend oil. In fact, I would probably be running Valvoline High Mileage in 10W30 or 10W40.
 
Messages
173
Location
Central FL
I've got an '03 GM that according to the manual, has had synthetic from day one from factory fill, to the very moment I write this comment.

Guess what? 18 years on, she's completely blown out an oil cooler gasket. Her block sweats all the way to the pan. I thought it was a rear main seal, but it's Teflon. Nearly bulletproof. Mirror and a flashlight later, it's the back of both valve covers that leak. The fix?

Keep feeding her Corvette spec oils.

Swap the cooler Bypass gasket.

New grommets and seals in the valve cover to be done the minute the sky stops dropping liquid sunshine and lightning like it was the apocalypse.

If it's going to leak, synthetic is not to blame. It's your seals that are *already* dried out, cracked and broken. Synthetic may easily *expose* them due to the properties of an ultra- refined oil once it clears the residue left by years of conventional oil.
Modern synthetic oils causing seal and gasket leaks is gone the way of the Do-do. The chemistry has greatly advanced since the mid-70's and are completely compatible.

Swap freely with confidence. If she leaks? It really, honestly needed fixing.
 
Top