Re: Regular Oil vs Synthetic Oil -EricTheCarGuy

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I knew the original video would spark discussion and apparently it’s caused quite a stir over at iATN. I also felt that some of what I said in the last video needed clarification. For those reasons I’ve made this Re: video. I’m not going to claim to be an expert on oil, I’m just speaking from personal experience. I still don’t think I’m done with this topic and I invite any ‘experts’ who wish to express their opinions on this topic to join me in the next video(s). If you wish to participate in a future video on this topic please contact me at

Here are links to the videos mentioned in the video.

Original video:

Subaru Trans fluid: Part 1

Part 2

Subaru Differential Fluid:

V6 Valve Adjustment: Part 1

Part 2

Discussion about this topic:

Stay dirty


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Author: Rafael


45 thoughts on “Re: Regular Oil vs Synthetic Oil -EricTheCarGuy

  1. Awesome video. Quick question, I'm switching from conventional to Amsoil signature series on my 2013 nissan rogue with 103k miles. The signature series says 25k but I'm thinking I should change it around 15k-20k due to sludge build up. Is this a good observation? And should I jump right into the signature series 25k or start with something less. Thanks, any advice helps. Cleary I'm not an expert, that's why I'm here.

  2. It is really difficult now to determine if you are truly buying synthetic oil or not. This is because of Castrol Syntec oil. Syntec is not made from a class 4 PAO true synthetic base oil but was just a class 3 higher refined conventional oil. They wanted to be able to add the word "synthetic" to their bottle because synthetics were becoming popular. Normally, only class 4 or class 5 base stocks are considered full synthetic oils.  Mobil simply filed a complaint with the National Advertising Division of the Better Business Bureau in the US claiming that Castrol was engaging in false advertising by calling Syntec "full synthetic" since it was now being made with Group III base oil. Castrol was able to present enough "evidence" to convince the NAD that Group III base oil could legitimately be called synthetic, so they ruled in Castrol's favor.  The NAD is merely a self-regulatory arm of the BBB and has no legal standing whatsoever in the U.S. Hence, their ruling in this matter does not make it "legal" to claim that a Group III oil is "synthetic." It merely means that for any entity willing to abide by the NAD's guidelines, a Group III oil can be ADVERTISED under those guidelines as a synthetic.  So, what this all means is that any Tom, Dick, and Harry can come up with a conventional mineral oil and refine it better and call it synthetic, even though its base oil is not really synthetic. This is why you will never see me buy Castrol oil for my automobile. Here's a breakdown of base oil groups. Base Oil Groups. Almost all industrial lubricants now come from base oils. The American Petroleum Institute (API) has 5 base oil designations. The first three groups are derived from crude oil (mineral oil); Group IV base oils are fully synthetic; Group V is for all other base oils not included in Groups I through IV.

  3. The more short trips you take without warming up the engine fully, the more water will end up in your oil pan and this water is a primary cause of producing the acid in your oil. These acids are a primary cause of sludge produced in an engine. I've been using synthetic oil since 1971, continuously, with no oil-related problems.

  4. This is a very good & honest explanation of what can happen both good & bad depending on how each car owner decides to do with their car. I own a 98' lexus gs400, only synthetic oil, changed every 2k miles, premium fuel only, now my car is 23 yrs. old, has 196k miles, & drives awesome!

  5. I had a friend (He made it to age 92) who was an airplane owner and a machinist by trade. His planes were from the 1930 to 1950's vintage. He did his own maintenance, which was always a problem, getting certified, because they had to be in perfect condition, and he was not a certified mechanic. Anyways, back in the 40's when your car was over 50000 miles you were considering having the engine overhauled. The engines were well made, same metals, and to the same tolerances, but still didn't last. What was different was the OIL. As the oil improved so did the mileage. The oil today is far superior to what was available 70+ years ago. I have 331000 miles on my 2000 Ford van. The rust will win but it runs great. And I use the Synthetic.

  6. What about oil viscocity! I have a brand new car that specs 5w40 in the manual as the engine oil it’s build and ensambles with ….tho on my first oil change the car shop went we will replace that oil with 15w40 …. I went why? Why not 5w40 as the manual states
    They went be cause it damages your car …. and then a whole mess I decided not to accept instead I bought 5w40 full synthetic and now it’s awesome
    I also had my transmisión oil changed at 5k and thank god cause it was pitch black

    Another problem I had was that they overfilled my engine oil by half a liter ! It was way over full on my engine oil meter I told them and they told me that was better …I was so pissed

  7. Viscosity is the resistance to flow, if they are the same – it will not flow better, no matter which oil it is.

    10cSt Regular oil flows at the same rate as 10cSt Synthethic oil.
    The only thing that comes in mind – synthethic molecules are usually smaller so they could potentially get through the smaller clearances.

  8. Conventional oil with 20% marvel mystery every oil change. Vehicle will run for ever with NO sludge build up ever. End of story

  9. The most important thing is to change the oil frequently. Even synthetic gets contaminated, especially if you do a lot of city driving. Change the oil frequently and use one brand. You should last 300k miles like my Toyota has.

  10. i love my synthetic oil in the extreme cold, aftetr14 years using it and not having to plug in the car , started ever morning, no more wondering if it will start in the morning.,

  11. People neglect their cars for so long then try to rescue them at the last second negligence is neglence !
    TAKE CARE OF YOUR CAR leaving at the bottom of the priority list wait for it to blow up then fix it SYN. oil is not a magic wand !

  12. I've got a Toyota with 183k miles. I change oil and filter every 5k, but Toyotas got this ring issue. You just mentioned every 4k, but I'm wondering if I should be more frequent as it ages? I'm thinking of trying fully synthetic (since I can go back), filter doesn't need to be any better?

  13. The main reason you probably don't want to mix oils, synthetic or regular, is not problems with the oil. The main problem is the difference between the additives that can clash or interact badly with each other. It's a good idea to stick with the same brand of oil between oil changes.

  14. Answered my question! I'm getting convinced to change my Toyota over to synthetic. I've been using a blend but apparently my Corolla has a piston/ring issue where they get gunked up and cause oil to burn. I've got 183k mi, but compression is fine but now I'm noticing small drop in oil over time. My question was if I try synthetic, can I go back or am I committed? The other question is if I can still use normal oil filter.

  15. 2009 toyota Camry with 47k miles on started running full synthetic when i got her at 40k now when i got her she sounded rough but once i changed the oil to full syn it was so smooth and has been ever since bought to go get another oil change now. Also mixing conventional and synthetic was a thing every mechanic ive ever spoken to says never ever ever to do so ima go by the actual mechanic and not some guy on youtube no offense.

  16. Supertech oil is very good for what it is . Made by Warren distribution. It’s not amsoil but will do just fine.

  17. I recently put synthetic oil in my 04 grand marquis. I'm not sure what was in it before (I just got car and it was my first oil change). Definetly sounds lighter and I'm concerned of damage happening. It still needs a quart, can I get the last quart as conventional motor oil and mix it or should I stick to what's already in the car?

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