DIY Home Improvement Forum banner
1 - 20 of 23 Posts

·
Registered
Joined
·
1,896 Posts
Friend of mine was bragging he has not changed his oil in 30,000 miles and it looks brand new. I was sold, went out spent a small fortune on oil. I changed it at about six in the morning and by noon the next day I had hardly any oil left. That was maybe 20 years ago and I have stayed away from synthetic ever since.
 

·
Banned
Joined
·
17,158 Posts
Friend of mine was bragging he has not changed his oil in 30,000 miles and it looks brand new. I was sold, went out spent a small fortune on oil. I changed it at about six in the morning and by noon the next day I had hardly any oil left. That was maybe 20 years ago and I have stayed away from synthetic ever since.
The low oil was not from changing the oil. It was from not checking the fluid levels, which a lot of people are guilty of.

I have gone up to 12,000 miles between changes with the Synthetic High Mileage that we use in all three of our vehicles. I may have to put a quart in after a couple of months, since two of our vehicles are mostly in town driving. Have had no issues with anything else.

All engines use oil during the firing process, because each time the piston takes a stroke or the valves open, there is going to be a small amount that gets into the chamber that gets burned off during the firing process.
 

·
Breakin' Stuff
Joined
·
701 Posts
Synthetic oil is great stuff. It's my understanding the oil itself lasts a very long time and really it's the filter that ends up needing changed first.

A lot of cars that come from the factory with synthetic have recommended maintenance intervals of 10,000 miles or more.
 

·
Banned
Joined
·
17,158 Posts
Synthetic oil is great stuff. It's my understanding the oil itself lasts a very long time and really it's the filter that ends up needing changed first.

A lot of cars that come from the factory with synthetic have recommended maintenance intervals of 10,000 miles or more.
People do not realize that it was Germany and Japan who created Bio-Diesel and Synthetic oils during WWII. Synthetics have been around since WWII, when all countries had to look at alternative oil and fuel sources, if they were not able to keep a supply coming in.
 

·
Banned
Joined
·
17,158 Posts
You can go back.

The bigger issue is usually if you are running conventional and switch to synthetic after a while. If you have a leak with conventional oil, it will gush worse with synthetic.
That is actually false. Synthetic blends allow an engine to be able to not burn off the oil at high temps. It has nothing to do with how fast oil leaks if a seal goes.

Japan and Germany perfected the use of Synthetic Oils during WWII. Over time, Synthetic blends have gotten better, that they are now able to save on how much recycled conventional oil and refined crude's for oils.
 

·
Banned
Joined
·
30,022 Posts
Synthetic oil is great stuff. It's my understanding the oil itself lasts a very long time and really it's the filter that ends up needing changed first.

A lot of cars that come from the factory with synthetic have recommended maintenance intervals of 10,000 miles or more.
While you can run longer intervals on synthetics if the base numbers and additive packages are correct, the filtration of the oil isn't the limiting factor in many cases.

AMSoil does sell a remote dual filtration unit that keeps the oil darn near clean, but the additive and base numbers are what typically create the necessity to change the oil in a car.

That is actually false. Synthetic blends allow an engine to be able to not burn off the oil at high temps. It has nothing to do with how fast oil leaks if a seal goes.

Japan and Germany perfected the use of Synthetic Oils during WWII. Over time, Synthetic blends have gotten better, that they are now able to save on how much recycled conventional oil and refined crude's for oils.
Synthetic oils do, on average, have higher TFout numbers which limits their burn off and volatilization, however, I was speaking more to leaks at rubber seals and other gasket surfaces and not any consumable aspect of the oil.

Synthetic oils are usually both slipperier and smaller. If you have a seal (assuming that it is a post 1992 motor with seals that are rated for use with synthetics) that is leaking with a dino oil, it will leak faster with synthetic.

http://www.cenex.com/about/cenex-in...page/oil-and-lubricants/five-engine-oil-myths

This is an often-cited myth. In fact, if your seals and gaskets are in good condition, synthetic oil will not leak in your engine. Synthetic oil has not been shown to deteriorate engine seals or gaskets. But it might find an existing leak. The smaller molecules of synthetic oil are able to pass through very small cracks and crevices that the larger molecules of petroleum-based oil cannot. Eventually, those small cracks and crevices can lead to bigger problems — with or without synthetic oil.

http://www.aircooled.net/synthetic-vw-oil/
Synthetic oil causing oil leaks is another commonly spread myth. The truth of the matter is that if all your engine seals and gaskets are in good condition, synthetic oil will NOT leak in your engine. The myth started because on occasion, an engine will leak with synthetic oil, but not dino oil. The reason for this is that the smaller molecules of the synthetic are able to get past very small crevices, where the larger molecules of dino oil cannot. But this does not mean that the synthetic oil has caused the leak, it simply has “discovered” an infant leak, and regardless of what oil you are running, this infant leak will eventually grow to a size that will allow dino oil to occupy and pass also. Synthetic oil has not been shown to deteriorate engine seals or gaskets. It is not some evil solvent that will break down sealant, or anything like that. Like was said earlier, it is just a man-made base stock, that is uniform and smaller in molecule size than dino oil. Nothing more, nothing less.
I have seen cars that showed no signs of leakage start leaking with synthetic oils. Now, this could be a function of several things that all existed prior to the synthetic oils, but the combination of the smaller and more slippery molecule can manifest as a leak.

Synthetics tend to have a better additive package as well and I have seen motors that were previously run on conventional oil get "cleaned" by the higher end synthetic. In doing so, it scrubbed out some of the sludge that was previously band-aiding the seal that now started to leak.

Again...none of these things are the fault of the synthetic oil and I still run them in every single one of my cars, but the potential for a more significant leak where one already exists is definitely there with synthetic oils.

Very reasonable trade off in my opinion based on the better performance.
 

·
What is that?
Joined
·
1,030 Posts
Rule of thumb. You can go from synthetic to conventional oil but not from conventional to synthetic as synthetic washes the engine and it will wash the conventional oil debris to the sump and stop it up. See it too many times. If the engine doesn't have too many miles, rule is moot but if you do, rule isn't. jmho:vs_cool:
 

·
Banned
Joined
·
30,022 Posts
The question becomes...why would you? Synthetic is not that much more than good quality conventional in many cases.

Walmart has great deals on Mobil 1 in the large containers and if we are talking about a 6 quart engine, you would save about $12-18 per oil change if all other things are equal.

That is $1.80 per 500 miles. That's a pack of gum.

With how expensive motors and components are today, seems like a wise investment to me.
 

·
Registered
Joined
·
399 Posts
Discussion Starter · #15 ·
Thanks. The whole reason for this topic is about my daughter's car. She bought a used 2006 Corolla from a dealer, along with some free oil changes. They used a synthetic blend oil, and they told her she couldn't go back to conventional oil. The free oil changes are used up, and she was asking me about this.

It sounds like the dealer lied to her. What a shock !!
 

·
Registered
Joined
·
1,597 Posts
Thanks. The whole reason for this topic is about my daughter's car. She bought a used 2006 Corolla from a dealer, along with some free oil changes. They used a synthetic blend oil, and they told her she couldn't go back to conventional oil. The free oil changes are used up, and she was asking me about this.

It sounds like the dealer lied to her. What a shock !!
So much "professional mechanic" bunk out there, especially when trying to impress a woman (assuming of course that the mech was a guy....)
 

·
Registered
Joined
·
6 Posts
I'm not an expert but I thought I'd chime in since I asked a question on another part of the forum and I feel bad getting info without at least trying to give some back! I've been changing my own oil for a while now (as a woman, it's been helpful to familiarize myself with the bare minimum of car maintenance). I've successfully switched between synthetic and conventional, but WindowsOnWash is right...there are hucksters that try to sell you synthetic but are actually selling you. Here's an excerpt from an article about making sure to use full synthetic oil:

"If you do opt for the synthetic option, be sure it is full synthetic. Some companies offer oil that is a blend of conventional and synthetic."

Probably preaching to the choir here but I hope it helps someone! Nice to meet you all!

–Charon
 

·
Registered
Joined
·
15 Posts
Somewhat off topic but...You could always get the proof for which oil is best for your engine specifically:
I do oil analysis on all my vehicles usually once a year unless it's a "new to me" vehicle then I get one done each oil change for the first 3. It only cost 30 bucks and I have the results in a week or two. It helped me determine that Rotella t6 was best for my Cummins and that I could do an oil change every 8500 miles despite the oil change warning in my truck. I've also done analysis on my bike when I was using the factory oil which was sheering before my normal interval of changes.
http://www.blackstone-labs.com/ is what I use but there are others.
 

·
Registered
Joined
·
10,497 Posts
It sounds like the dealer lied to her. What a shock !!
Lets give him the benefit of the doubt. There is so much mis-information out there. Could be he actually believes this because "a guy told him", or because he "read it on the internet". Or he once knew a guy who switched from synthetic to conventional and the next day his engine blew up - so that proves you can't do it. For that matter, was this the chief mechanic at the dealership or a "service advisor"? Bet if you asked him how he came to that conclusion, he wouldn't have a good answer.

I always use Mobil 1 full synthetic myself. That was manufacturer's recommended oil on the car I bought back in the day. Sold that car last year, but still use the Mobil 1 -- its habit now.
 
1 - 20 of 23 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top