I’m due for an oil change on my 2004 Camry LE 4cyl. (180k miles) and noticed conventional 5W30 motor oil has mostly disappeared from online stores. I’ve also noticed the synthetic blends are selling for about the same price as conventional. Is it okay to switch from conventional to a synthetic blend at this late stage ? Also, I assume whatever I go with I should look for oil labeled “high mileage” ?
You can switch back and forth between regular oil, synthetic, or a blend whenever you want.
Tester
4 Likes
Make sure whatever oil you use has the API starburst on the label. And that it “S” rating meets the minimum specs published by the manufacturer. Google api starburst for more info. I think the current S-rating is SP. I use “high mileage” oil in my cars, but that’s just b/c it is the only kind I can easily find in a 10W-30 conventional dinosaur oil. Whatever is in it doesn’t seem to cause any adverse effects.
Google is your friend just put ( Conventional 5W30 oil ) in the search box . But like tester says just use 5W30 and drive on.
Thanks for the replies and good to know the different types of 5W30 will work out just fine. I was concerned b.c. I saw a Scotty Kilmer video making the rounds which kinda spooked me on synthetics for old cars.
1 Like
First rule of vehicle maitenance or repair is to ignore Scotty Kilmer .
6 Likes
I would defiantly run the conventional or blend in the High Milage…
I’m one to stay away from Full synthetic on on a high mileage older engine if it has not already been using it, if it has a weak seal, the full syn will find it and start leaking, seen it many times before… Seems like it effects crankshaft and camshaft seals more than anything else… Yes some get away with it but some don’t…
2 Likes
I have a buddy who tried full synthetic in his high mile Camry. Oil consumption went way up and he switched back to conventional. Totally anectdotal for sure.
I had the same experience in a 93K mile Chevy. It took 3 oil changes to clean out the engine with synthetic. Used a bit of oil for the first 2, quit by the 3rd change.
It should be fine to use semi synth. Just keep an eye on the level until you and the engine get comfortable.
I’d have no problem going to a ‘high milage’ 5w-30 blend. The additives should keep any leaks to a minimum.
1 Like
So if full synthetic is going to “find” a weak seal, why is that ? Is it less viscous than conventional ? Or does it have so many detergents/cleaners that it might erode a failing seal ?
Btw, I did finally end up with a blend… More Information for MOBIL 124404
Yes on your first 2 questions. It won’t erode a failing seal. High mileage versions of any kind of oil often contains an agent to slightly swell rubber seals to help reduce leaks.
1 Like
A full synthetic oil has a more uniform molecular structure. Let’s say the structure size is the size of a BB.
Where with regular oil the molecular structure varies from the size of a BB to up to the size of marble.
The reason why some worn seals leak with a synthetic oil is because of the more uniform structure of synthetic oil, it easily passes thru the worn seal. With regular oil with its different size structures, eventually the larger structures start to dam up the leak at the seal preventing the smaller structures from passing thru, so the worn seal doesn’t leak.
Tester
1 Like
I’m going to call “Bogus” on the “more uniform molecular structure theory” for similar weight oils because any size difference would only exist on the molecular scale, which is too small to make any significant difference.
Much more likely is that we’re looking at an old cracked and worn seal that’s already leaking and you just noticed it or the fresh oil just happened to remove years of crud from the leaks.
For a more plausible explanation from Summit Racing .
Either way, the only real leak fix is to replace the seal.
Tester
That is exactly what your Summit racing guy said in the video you posted?? And basically the same thing Tester just said…
I have seen, done or delt with well over 50,000 (that is a very low est, realistically over 100K) oil changes over the years, and I have seen many oil leaks come from the use of full syn oil being used in a high mileage engine that had never ran full syn before…
Call it what ever the F you want to, real world, engine wasn’t leaking (may have been seeping) before installing full syn oil when never used before and now it is dripping while you are looking at it… i have also slowed down some or a lot the leak by going back to reg or blend high mileage oil and kept an eye on it for many more oil changes…
I disagree. Molecular sieves operate in the premise that some molecules will pass through the sieve and others won’t. On a smaller scale, I have seen pressurized systems that won’t leak air but will leak hydrogen, a much smaller molecule.
2 Likes
Long ago I recall that while developing synthetic oils it was discovered that one variety caused rubber seals to swell while another caused seals to shrink. Obviously the situation was remedied???
IMO both oils did the same thing, just at different rates. The oil that shrunk the seals started out swelling them. The solvent (synthetic oil) mixed with the molecules in the seals before it dissolved the external layer. The oil that swelled the seals didn’t have enough time to dissolve them.
So, yeah, they must have solved that problem. Part of the solution was not using either of the synthetic oils you described.
What were the oils that caused leaks and were not marketed BTW?