Considering Switching to Full Synthetic Oil

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You will see oil leaks where you didn’t before, going with full syn on an older vehicle with lots of miles. It has a different viscosity than regular oil. Been there, had it happen before.


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I believe the viscosity isn't really different. A 10w-30 or 20w-50 should be the same in synthetic or conventional oil. I think the reason you start seeing oil leaks in old(er) engines is the regular oil builds up sludge and goo and using synthetics in those engines cleans that gooey stuff out which then exposes the space to leak.
 

go_deep

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2018 Chevy 2500 gas 161k miles 10k mile synthetic oil changes. Bought new.
2014 Chevy traverse 143k miles 7,500 mile synthetic oil changes. Bought with 56k miles.
2012 Nissan Titan 151k miles 7,500 mile synthetic oil changes. Bought new.

Zero engine issues with any of them.
 

Backyard

WKR
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It has the same viscosity as the same rated conventional oil. The better detergents of the synthetic broke down sludge that was covering up holes that should have already been leaking.

Thanks for the correction. I knew I could count on at least one, if not a complete new topic.


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2531usmc

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Do all oil changes myself and run full synthetic in my 2016 Duramax 2500. Ran it in my 2007 1500 GMC gasser before that. The sensor will let you know when it’s time to change. It varies by how much you tow and other driving habits, but generally I don’t go to zero any sooner than 8000 miles.
I was surprised to see "sensor will let you know when it’s time to change. It varies by how much you tow and other driving habits". I always just assumed that the sensor was just a mileage counter.

Does anybody have any insight into how they actually work or function?
 

Marble

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If someone is really concerned and wants to know the actual quality of oil left after a certain amount of mileage, there are some places that will test the oil and give you a full report. I haven't done this, but when I was racing often, several of us would send oil in and see how it lasted. It's been so long I can't recall what the results were.

I like the 5k interval and full synthetic. It gives a chance to inspect brakes, other wearables, general inspection, tire rotation, air filter check etc. I tow a lot with my truck. It's normal for me to have 10k in combination of the trailer, rack and bed with product.

My son decided to go 10k, his air filter failed and he didn't know it. He then had to buy a new turbo for his 2016 Super Duty. ~$4500

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Jethro

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I used conventional oil @5k miles until couple years ago. Got hard to find conventional at the store. Switched to full synthetic and bumped interval to 6500-7500 miles.
 
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Dec 27, 2015
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4.7 - 10k - full synthetic - 230K - runs great

Buy the good filters (extended) and a fumoto valve.
When I had a Tacoma, I was surprised how small the filter was...Same part# as Tundra. I did some research on the drainback pressure valve and matched up a Wix/Napa Gold part that had over 150% more media than the Toyota spec and ran that for over 100k.
Did my own oil changes at around 7500 miles or so.
The engine was the only part of that car that was worth much at 180k miles.
 

Bugger

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I was surprised to see "sensor will let you know when it’s time to change. It varies by how much you tow and other driving habits". I always just assumed that the sensor was just a mileage counter.

Does anybody have any insight into how they actually work or function?
It’s not actually a “sensor”, but an algorithm that factors engine load and temp over mileage and time to indicate likely oil condition. Some people see it as a money grab to get people into the dealership more often but I think it’s smart to dummy-proof intervals for those who run their trucks hard and don’t understand why they’re getting knocks and leaks at 50k miles doing max intervals.
 

Beendare

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I watch my oil, if it has a dark tint- I change it...but sometimes I can go 7-8k. I usually do 5k.

When you watch the YouTube guy that tears these busted motors down on vid, the internals that failed is almost always due to gunk and oil failure.

It's cheap insurance to change oil.
 

tony

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You all change oil!? :D

I just pay ford to do it. I usually unload my vehicles after I pay them off. So while I take care of them and wouldn’t put dollar general oil in my truck, I really don’t care otherwise.
I used to change my oil and do routine service when I owned a house. I gave it to the ex as it made more sense for her to keep it.
Time I gather my shit from storage, take it to my apt, do the work, clean up, get rid of the oil, take my shit back to storage.
Man, $80.00 to the dealer is money well spent
Pretty sure my 4 banger ranger says its ok to change its life blood at 5k as well.
 

sndmn11

"DADDY"
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All oils are not created equal, just because it is synthetic doesn’t mean it’s a good oil, also some cases, a semi synthetic or mineral oil can outlive a synthetic with the right additives. I am a reliability consultant in the lube industry, specifically high quality oils and greases along with lube systems. A good quality oil can easily run 10k and I have seen testing on over the road rigs in Alaska, about the worst conditions a truck can see, going over 60k between oil changes on specific quality oils with a good additive package, while doing filter changes every 10k. I personally go over 10k on my car and truck with no hesitation with the oil I am using.

Newer vehicles with engine clearance needs or high temp/low temp issues would be the only reason in my mind to go with a full synthetic. Synthetics don’t carry additives as well as mineral oils. Yes, the oil doesn’t break down as fast as a mineral but the additives are really what do all the wear protection. If it isn’t calling for a full syn in something like a 0w-20, 5w-20 or 5w-30 I would suggest going with a quality semi synthetic with a good additive package. If it calls for a 10w30 or 15w-40 I would only suggest a semi syn or a mineral oil with a robust additive package.

Edit: I should also add, full synthetics are not bad, I should have said the right syn with the right additive package if they are calling for a full syn, which most newer vehicles are. A cheap full syn from tractor supply might only get you 5k, a good syn oil with a good additive package can easily go over 10k. Just research that it is a good additive package in any oil you plan to run it ver 10k or better yet, get an oil test done with the oil you are using at 10k and see how it is holding up. Test will cost you about $30 and you might find you can go 15k or 20k and get a baseline. Might save yourself hundreds in oil thru a year.

What is an additive package?
 
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Aug 14, 2023
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When in doubt change it out, car manufacturers have interest in getting you through the warranty period without issues so it may be "recommended" to change oil every xxx miles with full synthetic. I have always leaned toward caution and change it out every 5000-7500 even with full synthetic unless I have no intention of keeping the car long term.
 
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I only use Amsoil, change filter at 5k and add a quart. At the next 5k, or 10k total for that batch of oil, change oil and filter together. My truck is an '05 and that is what it has been since the engine was broke in.
 
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Aa
What is an additive package?
additives are added to the oil to enhance the performance of the oil. An example would be something to prevent rust, or remove water, prevent wear at a higher level than oil can do itself, clean the engine or clean the oil as it is worked. Diesel oil has more additives than any other oil, or it should. It is also the hardest worked oil from all angles because of heat, dirt and so on. Gas oils are not to far behind and also should have these additives. This is where an oil can be good, but it might not do its job if the additives are not present to help. This is the difference between a cheap oil and a good oil.
 

sndmn11

"DADDY"
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Aa

additives are added to the oil to enhance the performance of the oil. An example would be something to prevent rust, or remove water, prevent wear at a higher level than oil can do itself, clean the engine or clean the oil as it is worked. Diesel oil has more additives than any other oil, or it should. It is also the hardest worked oil from all angles because of heat, dirt and so on. Gas oils are not to far behind and also should have these additives. This is where an oil can be good, but it might not do its job if the additives are not present to help. This is the difference between a cheap oil and a good oil.

How does one know what additives there are? The quantities, etc? If the combination constitutes a good package?

I can read on the front of the bottle that there are "additives for wear protection" on just about all of them.
 
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