I cleaned up my Blazer today and did an oil change to try and figure out this oil leak problem I've had for a while. It's only recently gotten worst, so I need to figure out the cause before I can begin my 450 mile weekly commute on this Blazer again.

I came out into my garage this evening to check on things. At first I thought maybe it was a front seal leak that I discussed in another thread. Tonight however, I found a small puddle of oil on the floor under the oil pan.




I have not even driven her today, let alone run the engine in place. I ran the engine for a bit before the oil change to warm it up, and she's been cold since then.

This seems like an oil leak I shouldn't do 70 mph highway driving with.


So now I know the where (rear seal), but not the why.
Why did the rear main seal go bad? She wasn't leaking when I bought her 4 years ago. She started to a tiny bit in late 2018, and it's only slowly gotten worst since then.

Now I need to ask if it could have been the oil I was using, or do seals tend to go completely bad within a year?

Since I started doing my own routine preventative maintenance and restoration on this Blazer, I switched the brand of oil from the Walmart Supertech 5W-30 to the Castrol 5W-30 Ultraclean. Both conventional oil (so I think).

I used the Castrol Ultraclean for about a year because Scotty Kilmer on YouTube had a video about oil where he highly praised the Castrol Ultraclean for high mileage vehicles that didn't get serviced enough (Because the previous owner of this Blazer had it in storage before he decided to sell it).

This is the bottle of Castrol Ultraclean I've been getting off of Amazon.

When I went looking for it, I searched on Amazon for "Castrol Ultraclean 5W-30 Conventional". This product was on their first page of results. So, it showed up in my search results, Amazon says it's compatible with my model Blazer, and no where on the bottle does it say "synthetic". It doesn't say "conventional" either, but because ot didn't explicitly say "synthetic", I thought it was safe to use so I did for about a year.

The reason why I stopped using it is because I can't find this exact bottle anymore. So I switched back to the Supertech conventional. This switch back was very recently, and seems to be around the time this oil leak suddenly got worst.

When you go searching for the Castrol Ultraclean on Amazon, you get the same product under the same search query, but the bottle now has a new label that says "synthetic blend". I don't want synthetic oil and thought that's what the new bottle is. Amazon got an ear full of me when I was battling their refund department for a falsely advertised product.

Back then when I complained to Amazon about it, their listing had an image of the bottle without the "synthetic blend" label, but when I got the product in my hands, it said "synthetic blend", and I didn't even notice it until after I opened it. Castrol's marketing team made it very subtle.

https://www.amazon.com/Castrol-03096-ULTRACLEAN-5W-30-Motor/dp/B00GTOJK0C/ref=mp_s_a_1_3?dchild=1&keywords=castrol+5w30+conv entional+oil&qid=1592713263&sprefix=castrol+5w30&s r=8-3

This is Amazon's listing as of today. Can you spot the difference between this and my photo?



So now I need to know of this specific Castrol oil was mislabeled from the beginning and I have, in fact, been using synthetic blend oil.

Has anyone else experienced this?
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A little online research leads me to believe that it has always been a blended formula and they merely changed the label to reflect it. Here's an example:

https://www.bobistheoilguy.com/forum...GTX_Ultraclean

 

Is there a common part number?

I had a similar issue with Valvoline gear oigeart took a little digging but i was able to create my own cross-listing for it.

 

The drip in the upper photo is enough to make that size of puddle. Ive driven "OLB's" all my life (Oil Leaking ____es)

Welcome to the club. At least its not a Chrysler product- to drive a Dodge, have to strap a 55 gallon drum of oil on the roof with a drip hose in the crankcase.

Using a "cleaner" oil like that (which certainly has more cleaning agents in it) will accelerate leakage because itll erase the crud that helps seal the worn out seal.

Castrols stuff is first rate. have used it for 30 years.

Id been using Wal Mart special junk then switched to A big name semi synthetic SN grade oil. MAJOR improvement in oil life!

And got teh semi synthetic for $2 a quart at a farm store!