Is Synthetic Motor Oil Bad For Old Cars?

I would prefer conventional motor oil over synthetic motor oil any day!

I recently put a full synthetic oil on my last oil change and I’ve noticed a weird rattling sound coming from the engine since that oil change. What could that be about?

Question is not can you use it in old cars the question is can you switch to synthetic oil in a car that has always had conventional oil in its engine.

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Why does Mobile1 CLASSIC (high zinc) come in 10W30 but not 10W40 for summer.???

If your car is using oil and you're using synthetic oil switch over to regular motor oil and it will use less oil a lot less

My 455 pontiac destroyed my cam after only 200 miles. The story is that I wanted to take my pontiac from Denmark to Belgium to see a race. I had been using castrol RS 10w60 (now edge) for multiple yeards, but I thought I was having to much oil pressure when doing 60. Since I was about to drive 600 miles I switched to Mobil 1 10w50. Oil pressure fell a bit (as intended) but around Hamburg my engine misfired and when I reached Belgium I was driving on 6 cylinders. If you are driving a flat tappet engine please make sure the ZDDP content in your engine oilis high enough. I wasn't aware of this before the oil switch, but I certainly am now...

Ford Taurus 07 over 2'0000 miles no bad leaks older engine leak some maybe half a quart 3000 miles don't burn oil lots of power Mobil 1 seven years Mobil 1+filter the best engine made 3.0 v6 Vulcan engine

I appreciate your channel and have watched most of your videos.

I watched this one all the way through, hoping for an answer about using a synthetic oil in an older high-mileage engine with a flat tappet cam. Can you answer that question please? The zinc/ZDDP zealots are adamant, but have no actual data.

Thank you!

I put 0w12 in my 1996 ford f150. I can't keep it in there! Someone keeps stealing it out of the bed.

I had a customer that used Mobile1 synthetic for 120k miles in a Harley Evolution eng. No leaks or oil consumption. He wanted it torn down for inspection. Every component was still well within factory specifications. Replaced gaskets never reuse, cylinder studs never reuse, rings never reuse and touched up valves and seats.

I used my two old mercedes 5w40 liqui moli top tec.
An 230CE 124 coupe
And an beutiful 190D 2.5turbodiesel.

To sum it up: Beware of Aunt Esther.

Use your own judgement here folks. Do your research. There isn't anything wrong with using conventional oil in an older vehicle especially if that is what it is used to.

It always makes me laugh when the argument against synthetic oil is that it cleans yer engine too good. When i hear that, i generally think, 'Trumpster'. I put my hand on my chin, nod and say, 'hmm...I'l keep that in mind. Thanks'...And chuckle.

They say its ok to use synthetic oil in older vehicles they just dont explain all aspects. If the engine is burning even a small amt of oil say do to a valve guide seal allowing oil to get to valve especially an exaust valve will most likely result in failure , the synthetic has a higher BURNOFF temp everyone agrees ....the oil residue builds up on the valve = overheats , then that cylinder . I lost 2 engines to this 1 simply due to trust in the hype .another i added 1 qt of synthetic . 2 good running engines ruined😢😢😢

Good job but can you please do on for old diesel? Looking for info on my 87 6.9 f 250 with
175 k. Always change at 3 k at this point but looking for the new info that seems a little scattered. Thanks

Rotary Engines are a fail design, proven many times, no matter the improvement, it sucks

Very well presented and informative. Thank you.

If synthetic oil is fine to run in old cars then explain to me why it destroyed my 25,000 mile small block chevrolet in my 71 C-10 pick up. I changed from Castrol GTX 10w40 to Mobil 1 full synthetic oil and within a week it wiped out the cam and lifters and contaminated the rest of the engine with metal particles which then took out the number six rod bearing. I had a very reputable engine shop go through the engine and the first thing he said was synthetic oil does NOT have enough ZINC or DDT in it to properly lubricate a flat tappet camshaft engine. So you need to stipulate that when you're making a video and tell people that synthetic oils are fine for a "OLD CAR" because that is very misleading. Since rebuilding the engine, all I have run in it since has been Valvoline VR1 and it now has 90,000 miles on it.

Pretty much any vehicle made after 1990 was designed for synthetic motor oils. It's only those dinosaurs from the 1970's and earlier that may still be using seal materials that could begin to weep or leak due to the superior stability of synthetic oils.

What oil is recommended for 1fz fe engine? 150k km milage?

I have a 1993 Ford explorer sport with 250,000 MI I used to use 20. 50 oil winter summer whatever I do now use whatever 40 weight oil I can find that is synthetic and it seems to be doing okay but you should change the oil every 5,000 mi that what I've always done so there you go..

Answer=NO. Finished. Easy.

In 2025, I use Total Quartz 7000 10w-40 with Semi-Synthetic oil base, I use it for Honda Supra Fit New (Wave 100s) C-Series C-100 engine, its performance is still safe and even extraordinary, considering this motorbike was released in 2006, In Indonesia with tropical seasons, whether it is hot or rainy weather, its performance does not decrease

So whats considered old these days in car years? Ive got a new car, but i mainly drive my 99 grand marquis. 185k miles, its my daily, and couple of 8 hour road a year. Ive been using 5w20 conventional in the grand marquis, but have noticed the last couple oil changes its been low. Like i checked it today and it was 2 quarts slow. A year ago it wouldnt have used any oil. No leaks either. Maybe i just try some sea foam or something like that, see if it'll stop burning.

Hello dear
What about gulf countries
Temperature of whether not less than +40* c
Car manufacturer required 5w30
It is old car with mileage of 340,000 km
Can i change viscosity to 10w40 semi synthetic oil

4:57 5:46 8:58 Oil pressure symptom: idling.

Yeah yeah yeah.... well , thing is people still buy farm tractors that are new , but the design is very old. Like 40 years old engine , just manufactured recently okay ?
Some did try a "new and more advanced oil" . Those got busted. So they did proove its a bad idea.
So then , people allso buy brand new tractors. And those are recent designs. Tractors are under a lot of load , ideal testbeds . Well take a guess , those who get the new tractors and use oldschool regular oil , are they happy ? Yess they are. Those who use the manufacturer rated synthetic oil are not happy. Engines wearing out in 10k operating hours is a joke. Run it with old oil ? Yepp , you get least 3k more hours. So screw it.

Changing from mineral to semi synthetic and oil not turning black? Any thoughts??

Sounds like they are trying to sell more oil!

You should use high milage oil if your engine is burning oil.

FIA banned mineral and semi-synthetic oil for F1 cars.

I'm not an expert on Rotary engines, but high quality fully synthetic two stroke oil, which is meant to be burnt, forms a lot less deposits than old mineral oil or even synthetic based oil. This much I know from data and experience of seeing less deposits on the piston crown and exhaust port. I think Rotary engines recommend two stroke oil or something that can be burnt, so it stands to reason to use the one which forms less deposits.

Motorcycles here. Old motorcycles run absolutely fine on newer synthetic oil as long as the recommended grade is respected. New bikes usually have tighter tolerances, but mineral doesn't mean better with higher tolerances. There's a misconception that 10w40 is thicker than 10w50 for example. It depends on the temperature your engine is running. Some people think that 10w50 is thicker than 10w40. 10w40 will become thinner only if the temperature exceeds the one tolerated by '40'. If you run an engine on 10w50 it'll either be the same or keep its viscosity better if the temperatures it reaches are higher. Same for Winter, 10w if you live in warm areas won't be different to 5w or 0w. 0w won't become too thick if you start your engine below 0 celsius. I don't know the exact temperatures, but broadly speaking, it's not the viscosity that chances, but the temperature spectrum that an oil can keep its viscosity consistent. For example, if you use a yamaha R1 you'll be fine with 10w50 or even 15w50 if you use it in summer only in the mediterranean, even 10w40, good oil of course, would do if you see that your temperature gauge barely goes over 90 celsius. If you hammer it down a racetrack at 14/15000 rpm lap after lap, use 10w or 15w60, as that should technically keep its viscosity under a lot of heat stress, usually 10w60 is sold as motorcycle racetrack oil. Maybe this misconception comes from the past when you had monograde oils 20, 30, 40 and so on. Those had a specific viscosity at a specific temperature.

Well I had a 2000 Chevy Silverado with only 60,000 miles on it. Up until then I had always used conventional motor oil. After asking every mechanic that I could find, it actually came down to a 50-50 decision that it's a bad idea to switch from one to the other! Half of them told me not to and the other half told me it would be OK. So I took the chance of switching over to Synthetic oil and within 4-5 month's, the front and back seals started leaking out of nowhere!!! That wasn't just a coincidence! It never leaked a drop of anything before I switched over. 🤬 In my own experience, I would never do it again!

I use baby oil 😉

No oil " reconditions " engine seals

My vehicle is on 145 000km. No oil leaks or engine wear. I've been using 5w30. Should I now change to high mileage oil because of the high mileage?

I switched to Mobile1 5-30 for my 1971 big block chevy. With everything else it runs better than ever. Word to the wise, if you switch to full synthetic, do a second oil change very soon after the first one, before 100 miles IMO, and even a 3rd before normal interval (e.g. 1k miles). Engine oils are NOT intended to be mixed (e.g., conventional/synthetic), drain only drains so much. I'll take my engine's word for it, never mind it's a science fact. That and you've basically cleaned the system. I changed mine 4 times over 1k miles, but then, it's a fresh restoration, and I really like my truck☺ Okay, once a year from here on out, (every approx. 900 miles), pinky swear, maybe.

I use conventional 10w40 in my older vehicles. They run quite and smooth, compared to the synthetic oil. Less valve train noise, more power, better oil pressure at hotter temps.
That's what they like so that's what they get

what about flat tappet cams that require ZDDP?

I remember when I was 16 this was a huge debate.

More bad advice. If a car has quark, or rope seals synthetic. Molecules are too small. I know this from experience.