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Discussion Starter #1
Guys,
Tomorrow I think I'm going to pick up a jug of Pennzoil high mileage oil, and wanted to ask y'all if anyone has had experience with this type of oil before, and if you noticed any improvements?

Primarily the only thing that really bothers me at this point in time with my car is the few small oil leaks. I'm quite sure that the oil pan is leaking at the front, and also the full-round rear main seal leaks.
Even at 181,000 miles my car still doesn't use any oil between the 7,000 mile intervals as suggested by Blackstone Labs.

I'm curious if anyone has made the switch from conventional dyno-juice to a high mileage oil, and had various seals come back to life, so to say?

I prefer Pennzoil because of the higher zinc content and read that the high mileage oil is recommended for engines above 75,000 miles.

I've got nothing to lose, and the only down side I can see would be the possibilities of oil consumption past the piston rings, or various seals leaking more.

Just curious if we have any folks with first-hand experience that would care to share a story or two about it.

Thanks!
 

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since your not loosing any oil on a 7K oil change stay with what your using .. what oil are you using for the 181K miles ?

my 1983 V8 GM sedan ran on castrol 5-30wt conventional and did oil changes at 4K miles.. at 375K miles I had no leaks or any engine work .. just a water pump and starter motor.. I used 1/3 QT of oil even at the 300K miles on it ..

some have had problems with the high mileage oil on trucks GM...never used the high mile oil because of the complaints and why would I because I never had any engine issues with the oils I use ..
 

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I have used high mileage Castrol in my other "over 100k mi" cars. My understanding is it is blended with additives to help keep older seals soft....IDK if it actually does. In the big picture I didn't notice any difference in oil use. YMMV

I believe high mileage blends are also "semi" synthetic. Some feel synthetics are "thinner" and seal leaks are a result. I personally never experienced this using semi synthetic high mileage oils
 

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Discussion Starter #4
since your not loosing any oil on a 7K oil change stay with what your using .. what oil are you using for the 181K miles ?
Traditional Pennzoil dyno juice.
 

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Discussion Starter #5
[SNIP]

I believe high mileage blends are also "semi" synthetic. Some feel synthetics are "thinner" and seal leaks are a result. I personally never experienced this using semi synthetic high mileage oils
-THIS- is why I have been hesitant on any older vehicle I've had to switch to synthectic, or in this case a partial synthetic. I don't have any first hand experience, or known anyone who has, with the two items that I've always read about.
  1. Oil consumption past the rings
  2. Seals starting to leak more
That's why I thought I'd post the thread and see what results I get from other LT1 engine owners.
 

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My personal experience is that synthetic oils have better detergent / cleaning performance and it's the removal of sludge that causes leaks, not seal damage. One of my prior roadmaster wagons had not had the oil changed in a very long time, so much so that you couldn't even see the lifter spider/bolts in the intake valley, and when I would run synthetic, it would literally fill the filter with sludge, far faster than non-synthetic oil.

So.. if your engine is sludgy, run synthetic and buy an oil filter cutter tool and think about swapping the oil filter halfway between oil changes.
 

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Discussion Starter #7
[SNIP]

So.. if your engine is sludgy, run synthetic and buy an oil filter cutter tool and think about swapping the oil filter halfway between oil changes.
Nah, my baby is clean as a whistle. I can say that because I just recently (Last oil change) had the intake manifold off to fix the rear valley seal leak.

Even the folks at Blackstone Labs were surprised by the samples I had sent in, and that's how I got up the the 7,000 mile oil change interval, after working with them over the course of 6 or so samples.
 

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Nah, my baby is clean as a whistle. I can say that because I just recently (Last oil change) had the intake manifold off to fix the rear valley seal leak.

Even the folks at Blackstone Labs were surprised by the samples I had sent in, and that's how I got up the the 7,000 mile oil change interval, after working with them over the course of 6 or so samples.
my guess is you do long drives not 5 mile runs short drives in cold temp with conventional oils will cause the sludge..on my 1983 sedan I had no sludge did 50 mile runs 5 days a week and did the long oil drains like 40 MIN to remove all the old oil .. I also cut open the filters just to see how the media looked and it was with not much discoloration and the oil was just slightly darker than new oil ,,..

on my 2016 toyota truck I use 0-20wt mobil synthetic and the oil old looks like the new @7500 mile oil changes .. also A PITA to see on stick where the oil is because it is so clear ..
 

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Discussion Starter #9
my guess is you do long drives not 5 mile runs short drives in cold temp with conventional oils will cause the sludge..on my 1983 sedan I had no sludge did 50 mile runs 5 days a week and did the long oil drains like 40 MIN to remove all the old oil .. I also cut open the filters just to see how the media looked and it was with not much discoloration and the oil was just slightly darker than new oil
This is true. Also, I've got the service records of the previous owner who used to take the car back to the dealer for every service, and he did quite well with the oil changes and maintenance.

The color of my engine's oil doesn't stay golden; it does turn darker. More of a coffee color than a pitch black. I've never cut open a filter, but I may just do that tomorrow after I change the oil for $hits & giggles.

This engine will be the test/guinea pig for the partial synthetic oil changeover.
 

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given your motor is clean and you have had several blackstone reports, which I assume are good, The semi-synthetic high mileage will be fine especially if you are going 7k mi change intervals (IMHO a bit much for dino oil)

With that said I use dino and change every 2k mi per my builder. For me that is once a year. I have always done my own oil changes as it gives me the opportunity to check everything out "from under" the car :)

FWIW I did send in my last oil to Blackstone for the first time. All good according to them

Every motor and use is different so do what you feel works for you.

short trips where the motor does not get hot enough to burn off the condensation (water) in the oil which happens from heat/cool you need to go much shorter on oil change intervals.
 

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It's worth noting that I had a 1.5 mile commute in Syracuse NY (in my sludgemaster LT1) and rarely got the motor up to full temp more than once or twice a week. Blackstone Labs analyzed it and found NOTHING wrong with the oil. So... once or twice a week is all you need.
 

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I would use Penzoil Ultra Platnum and be done with it all.

KW
 

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I also have 182k miles on mine. I have used Amsoil synthetic since it was new and I have no leaks. I agree with jcat, I would just stick with the same oil you have been using since it has given you good service. Scotty Kilmer did a youtube video and he swears by AT205 for small engine leaks. Most people will think its snake oil, but he gave several examples of it working for him. You might try using your same oil with a small amount of that added to it.
 

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when your engine is 20 plus years old small oil leaks will happen.. synthetic oil should keep the seals good ..dino oil with moisture absorption create acid , then the leaks .

I have a small leak on the O ring of the CPS.. but just a small wet spot . no drips.
 

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Every LT1 corvette came from the factory with mobil one. No reason to run conventional oil in an LT1.
 

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Every LT1 corvette came from the factory with Mobil 1. No reason to run conventional oil in an LT1.
I've agreed with this statement since my 1st 9C1-LT1 in '98, but GM did not.
Although 9C1s came with external motor oil coolers INSTEAD of synthetic oil, every other B- & D-car [and F-car] got dino oil, which I considered [then and now] a shame.
GM, however, probably figured most of the B- & D-car's target demographic, including police depts & taxi fleets, would dismiss synthetic oil as an unnecessary extravagance.

As far as I know, 'high mileage oils' are just Group2 &or Group3 motor oils with even more additives than regular dino oil. Color me unimpressed and unconvinced.
The best flowing dino oil or 'synthetic blend' 5W30 may be impressive off the shelf.
After 3000 miles, though, Group4 synthetic oils simply degrade far less in terms of cold-start protection and flow, burnoff, and yes, seal conditioning.

Simplest way I know to be 'pretty sure' I'm buying actual Group4 synthetic oil, is to ONLY buy 0W30 or 0W40, regardless of brand (coupons and sales and stuff).
 

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Discussion Starter #18
[SNIP]

As far as I know, 'high mileage oils' are just Group2 &or Group3 motor oils with even more additives than regular dino oil. Color me unimpressed and unconvinced.
The best flowing dino oil or 'synthetic blend' 5W30 may be impressive off the shelf.
After 3000 miles, though, Group4 synthetic oils simply degrade far less in terms of cold-start protection and flow, burnoff, and yes, seal conditioning.

Simplest way I know to be 'pretty sure' I'm buying actual Group4 synthetic oil, is to ONLY buy 0W30 or 0W40, regardless of brand (coupons and sales and stuff).
I've never looked at the group number, or really anything specific regarding engine oil. I looked up the oil I installed, and didn't see anything regarding group specifications on the Pennzoil web page.

Where's the group information typically listed you wrote about?
 

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Thank you, fbi9c1; much respect.
I've never looked at the group number, or really anything specific regarding engine oil. I looked up the oil I installed, and didn't see anything regarding group specifications on the Pennzoil web page.

Where's the group information typically listed you wrote about?
The vast majority of the motor oils that you can buy in a store will typically not list their Group designator.

From 'Synthetic' as the word relates to motor oil
Michael Trueba said:
API motor oil categories and what they mean
Group I — Solvent-refined crude oil.
High wax and aromatic (organic matter) content.
Used in low-grade conventional motor oils.

Group II — Hydrotreated crude oil refining process.
Less wax and aromatic content.
Used in the majority of conventional motor oils.

Group III — Wax isomerized or hydrocracked crude oil refining process.
Group III base stocks are considered synthetic because their molecular structures are altered through an intended chemical reaction.
Very low wax and aromatic content.
Used in the majority of synthetic motor oils.

Group IV — Polyalphaolefin (PAO) base stocks are chemically synthesized from ethylene. Used in some synthetic motor oils.

Group V — All other chemically synthesized base stocks, including all esters and polyalkylene glycol (PAG).
Used in the minority of synthetic motor oils.
If you do 'enough' research, you'll eventually find that Castrol got Group 3 base stocks to be re-deemed as synthetic, when they were previously considered refined crude oil.
Originally, Group 3 base stocks were, and still are, crude oil that are simply subjected to processes that yield superior results compared to Group 1 & Group 2.

To this day, Group 1, Group 2, and Group 3 base stock motor oils are not capable of 0W30.
0W30 will climb to the rockers more quickly and more uniformly than a Group 1, Group 2, or Group 3 5W30 [especially when it's colder than 0°C, and especially after 3000 miles].

Since I haven't time to compare which 5W30 motor oils are Group 4 and/or 5 vs which are Group 1, 2, or 3, I stick with 0W30 or 0W40, and change the oil and filter every 3000-4000 miles.

When they figure out how to make a Group 3 base stock motor oil that rates and performs as a 0W30, I guess I'll be willing to buy it.
By then, I'll be old enough to take Eddie Mack far more seriously.
 

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Discussion Starter #20
[snip]

If you do 'enough' research, you'll eventually find that Castrol got Group 3 base stocks to be re-deemed as synthetic, when they were previously considered refined crude oil.
Originally, Group 3 base stocks were, and still are, crude oil that are simply subjected to processes that yield superior results compared to Group 1 & Group 2.

To this day, Group 1, Group 2, and Group 3 base stock motor oils are not capable of 0W30.
0W30 will climb to the rockers more quickly and more uniformly than a Group 1, Group 2, or Group 3 5W30 [especially when it's colder than 0°C, and especially after 3000 miles].

Since I haven't time to compare which 5W30 motor oils are Group 4 and/or 5 vs which are Group 1, 2, or 3, I stick with 0W30 or 0W40, and change the oil and filter every 3000-4000 miles.

When they figure out how to make a Group 3 base stock motor oil that rates and performs as a 0W30, I guess I'll be willing to buy it.
By then, I'll be old enough to take Eddie Mack far more seriously.
Thanks. Now I've seen everything. I decided for the heck of it to look on Amazon for the Pennzoil 0W40 oil, and found that they now brands and sells jugs of oil. Wow, they've got their hand into everything these days.
 
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