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58Bonne's 1958 Bonneville

2019 June
of the Month

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What's the longest you all let an oil change go? I was running full synthetic oil..... 8k 10k 12k?????

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I use it in most cars I own because one can just tell it is better. The main reason is because it is just better quality oil it seems. Just to be clear the only improvement is constant viscosity? I still add a little STP oil stabilizer, If the bottle said use whole id use 1/3rd of it. 

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Posted (edited)
15 hours ago, Lynn5907 said:

I use it in most cars I own because one can just tell it is better. The main reason is because it is just better quality oil it seems. Just to be clear the only improvement is constant viscosity? I still add a little STP oil stabilizer, If the bottle said use whole id use 1/3rd of it. 

Everyone has their perception as to what something is or does, so if your oil works for you all’s good! Your question was oil change length, I replied 7 to 12 thousand is realistic, but what is your condemning limit? Is it only mileage? 

There is no definable control as to what synthetic oil is, as was proved in a lawsuit between Mobil & Castrol. Since then API has removed all references to Synthetic in their documentation regarding standards. "Full synthetic" is a marketing term and is not a measurable quality. The only thing that defines quality in an oil, be it synthetic or conventional oil, is the crude oil & components, as well as the additive package. Then std. SAE testing proves the performance of those oils. Most folks have no idea what the true performance of a specific oil is.

The two basic advantages in a synthetic oil is shear stability, (constant viscosity) & thermal break down, (elevated temperature), I.E. jet engines! If someone needs thermal break down protection in their car’s engine they have more pressing problems than oil! Thermal break down in an oil starts when the “oil” temperature reaches 375c or 700f.

The STP product you mention is basically a viscosity modifier, with possibly ZDDP or moly, but they don’t say. So I have to presume neither and if that’s the case, it’s only a viscosity modifier which basically defeats the purpose of a synthetic oil!

Edited by Last Indian
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Last Indian why do u say I'm defeating the purpose of the oil with stp. Yes I go by miles I'll never get to 3 months let alone 6 or more. I use stp for ZDDP and to help the oil so I thought. This car has a really long timing chain ... so then there is nothing as full sys oil just dino oil with packages... 700f that's a lot. Yes ur have some serious friction like a slipped crank bearing or something in that seriousness of nature...really I think 6k is good but I let it go for a while just to see and it was still amber at 9k and even 10k .... but you also ( I ) have to think that it needs a whole quart at about 4k to 5k and then every 2k after. I use walmarts full sys high mileage 5w30 

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3 hours ago, Lynn5907 said:

Last Indian why do u say I'm defeating the purpose of the oil with stp. Yes I go by miles I'll never get to 3 months let alone 6 or more. I use stp for ZDDP and to help the oil so I thought. This car has a really long timing chain ... so then there is nothing as full sys oil just dino oil with packages... 700f that's a lot. Yes ur have some serious friction like a slipped crank bearing or something in that seriousness of nature...really I think 6k is good but I let it go for a while just to see and it was still amber at 9k and even 10k .... but you also ( I ) have to think that it needs a whole quart at about 4k to 5k and then every 2k after. I use walmarts full sys high mileage 5w30 

Lynn, this is a little engine oils 101, and as a rule it’s pretty straight forward. I worked in this field for 40 years in R&D. Please take this as it’s given, just as informative information to digest.

All oils, synthetic & conventional, go through the same oxidative stress. All start at the same TBN 9-15 depending on mfg & type. All are depleted of the TBN by combustion which produces soot, even in a gas engine & causes TAN, that acid cause oxidation, which in turn causes etching and erosion of metal parts. Which in turn causes particulate in the oil which in turn causes more oxidative stress due to more heat from particles running into each other when pushed through small orifice. In the end this is called bulk viscosity, and has a small effect on small orifice areas like modern engines small bearing clearances & VVT components. Which is why maintaining oil viscosity is important and why synthetic oil is appealing.

Additionally there is oil shear. This occurs when oil is literally pushed in two different directions by two opposing surfaces, like a engine main bearing stationary and a rotating crank. This shearing action initially thins the oil viscosity within the first 1000 miles or so, but than it slowly thickens, but synthetic oil are resistant to shear. This makes them good for VVT applications.

With all that said the issues with this are, long before viscosity becomes an issue for an engine oxidative stress, acid, particulate contamination, fuel dilution, which does lower viscosity even in a synthetic oil become a condemning limit for the oil! Knowing those facts most people won’t pay twice as much for a synthetic oil just to keep the same interval of an oil change! So they push the change interval out farther and no matter how minimal the negative impact is on the engine, it is negative!

The STP deal! You said STP oil stabilizer not oil treatment. The stabilizer has no ZDDP or moly, it’s just a viscosity modifier! Which means it thickening your 5w30 synthetic! That basically defeats the purpose of the synthetic oil! The STP oil treatment has ZDDP in it, but that’s bad for the catalytic!

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Damn! Actually thanks that's the kind of info I was hunting for. It's an oil treatment not stabilizer but it is thick so I just assumed it was a stabilizer. Did not know it was bad on the cat but the car is at 282,000 soooooo the cat is already bad and I'm trying to make it to 300k +

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Posted (edited)

Lots of things poison a cat! Even engine oil! If you don’t have to go through an emissions test where you live it’s a non issue whether the cat works or not. The only thing that will occur, but more from burning oil than ZDDP poisonings, is a loss in power. If you don’t notice a loss in power don’t worry about it. Likewise if it was bad it would set a code.

Edited by Last Indian

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P0420 has been lit up for a wile just don't seem to bug the car. I bearly touch the gas to go sometimes. Great gear ratios. I can turn off the cat code to pass test then it pops up down the road in 100miles to 500. Just tryna to learn more about oils always been a thing of interest considering how close every engine is to self destruct at a moment's notice

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The P0420 code indicates that most likely the cat is gone! Code be an O2, but usually it’s the cat. It doesn’t sound plugged by your description of performance, but as time goes on it most likely will. Unless the cores been knock out?

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While you may not be in a state with emissions inspection, a damage cat-con is not a good thing for your car period. It will eventually plug or restrict exhaust flow and that add back pressure could damage your engine - in time. You engine is basically an air pump. If it cannot exhale, it cannot inhale. It if cannot do either - it will stop.

I've seen cars that have literally been so rich that they have blown out, melted, or destroy the cat-con. Not a good thing unless you are going full-time racing.

I won't get into the details of how a cat-con works but suffice it to say it is probably the most important anti-pollution device on the car.

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23 minutes ago, Frosty said:

While you may not be in a state with emissions inspection, a damage cat-con is not a good thing for your car period. It will eventually plug or restrict exhaust flow and that add back pressure could damage your engine - in time. You engine is basically an air pump. If it cannot exhale, it cannot inhale. It if cannot do either - it will stop.

I've seen cars that have literally been so rich that they have blown out, melted, or destroy the cat-con. Not a good thing unless you are going full-time racing.

I won't get into the details of how a cat-con works but suffice it to say it is probably the most important anti-pollution device on the car.

Copy that! We can all live a cat! Their so good now they don’t affect exhaust flow at all. Some of the high flow ones like I run on the Indian actually improve the flow dynamics of the exhaust.

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O2 have been replaced up and down stream. I think it melted the cat. The upstream o2 was melted lol. When I got the car only two cylinders fired and was dumping fuel down the drain. That was 100k ago so car got lucky it survived.. it should have washed the cylinders.. even diluted oil something like that. Frosty might remember me talking about that a wile ago 

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Posted (edited)

Yep yep yep..... thanks you all 

Edited by Lynn5907

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I do remember that discussion. This engine has seen a lot of hard usage (I won't call it abuse yet). I think it is about to beg for a tear down and inspection.

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Hey now! Lol. O tho the heater hose quick disconnect did just pop. Low coolant light came on I'm like shiiittt water pump first thought .. got blessed. Fix the hoses, flushed it and refilled with new coolant. Seems good to go. Frosty I'm still surprised this engine has made it this far. The dumb guy I got it from was just cracking away hitting gas petal on old oil .. oil pressure sensor was leaking everywhere .. alt was shorted out on the motor and only two cyls were firing... talk about a bet. You every have one of them feeling that it is a good car nonetheless????

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7 hours ago, Lynn5907 said:

 You every have one of them feeling that it is a good car nonetheless????

 

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Awesomeness.... ( I'll put the antifreeze in my carburetor ) roflmao 

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Not sure how to send the video from Facebook messager, but anywho. There is this guy using a torch on a shock assembly to separate it. Of course it work, but man that spring goes flying. That guy either A: has no brains B: balls of steel. 

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6 hours ago, Frosty said:

 

AHHH Speedy.......When Saturday AM meant something!!!!!

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For sure JustA! I would sit with my daughter and watch speed buggy, Scooby-Doo and the like! Good memories!

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