Why does my mechanic tell me to not make the switch to synthetic motor oil?

Question

I have a 1999 Honda Accord EX V6 with 145,000 miles and he says not to put synthetic in it. I just bought the car and it does not have synthetic.

Why would he not want that? What should I do? What would be a good sythetic for the car?

Answer 1

take the car to another garage and ask them what they think.  i had a 88 lincoln  town car. and i always put regular oil in it then the next time i had a oil changed i switched to synthetic and it didn't hurt my engine at all.   my crossfire has to have a certain kind so i have to take it to a dealer they are the only one who has this oil.  so check with the honda dealer  mechanic if you can use any kind of oil.

Answer 2

Synthetic will tend to clean out all the sludge and deposits left in your engine from extended use of regular oil. With the extended mileage between changes synthetic oils offer, you take a risk of plugging oil filters.  If you are heart set on making the swap, plan to change the oil and filter at the regular change mileage at least one time.  Some feel synthetic oils cause leaks in high mileage engines, but I have not seen that happen in my experience. I have had very good luck with Royal Purple.  

Answer 3

Your mechanic is telling you not to switch because synthetics have been known to destroy motors...if i understand this correctly the synthetic oil creates harder surfaces on break in than the petroleum based oil...when you make the switch to synthetic the break in starts again since the petroleum based break in is softer...thus destroying your motor from the inside out...they are only really beneficial if you push your oil to the very limit...Good Luck

Answer 4

i wouldn't do it either... and i use synthetic in everything.

the reason i wouldn't is this.  synthetic is much cleaner than conventional oil, so it will clean sludge out of your cars engine that the conventional oil leaves in place.  sounds good right?  it is, in a new low mileage motor, but in a high mileage motor that sludge and buildup is often hiding weak spots in your gaskets.  when it is removed your car will leak, the rings may begin to leak, all because your engine is now too clean for the condition it is in.

for first time use i never start a motor with over 80K on it on synthetic, you're almost guaranteed to cause a leak and absolutely hate it.

Answer 5

He want you not to use it so that you will visit his garage more when your car is not functioning right (easy wear and tear of the engine). Mobil 1 Synthetic oil is one of the best synthetic oil used by the public including myself.

Edit: Use your instinct and do what you think is right for you, not what your mechanic says. When in doubt ask other mechanic why (just a curiosity). I'm very sure your mechanic is totally wrong 100%...

Answer 6

Synthetic oil is far superior to any conventional oil on the market.  The reasons for your mechanic telling you not to put synthetic in is because maybe the engine has some oil leaks.  Synthetic oil is thinner then its same grade conventional counterpart and it will find these leak points faster.  Maybe the engine is making some kind of noise.  Again, synthetic being thinner, can make the noise louder or even cause more damage.  Another reason is the mileage that is currently on the engine, that engine has a lot of miles on it and synthetic oil could make the engine tolerances become greater then using a conventional.

Basically the rule of thumb is if you have used synthetic oil from the start you have to continue to use it.  Don't switch back and forth because even though you change your oil at regular intervals, you can never get all of it out and a pure synthetic oil (Mobil1) and conventional oils don't mix too well together.  

Answer 7

Perhaps your motor has an oil leak or two. Synthetic oil has a very aggressive detergent package to keep the inside of the motor spotless. It can actually uncover small leaks and make them bigger because of the strong detergent. If your motor has no leaks there's no reason you can't make the switch. Since your car calls for 5W-30 on the Mobil1 website their full synthetic will pour at - 52 degrees below zero Farenheight.Thats a full 15-20 degrees lower tham anybodys mineral oil. Colds starts is where 86% of all engine wear occurs. Since it flows easier at low temperatures your oil pump will deliver a high volume of oil to critical engine parts faster. 5W-30 creates less drag on the oil pump which will give you more horsepower and the oil system will pump a larger volume of oil through the oil galleries at all temperatures. A larger volume of oil cools frictional surfaces more efficiently than a higher viscosity oil. There are more EP (extreme pressure) additives in synthetic oil. It evaporates at a higher temperature than mineral oil. It flashes to fire at a higher temperature than mineral oil. Everyone knows full synthetic oil is more slippery than mineral oil so you may realize a bit of fuel economy.

If I were you go back to the mechanic and ask for specific reasons he would not recommend using a top quality full synthetic motor oil.

Mobil1, Valvoline, Havoline, Kendall and Quaker State are all good solid brands. Royal Purple is great but the price tag is stiffer than the others.  

Answer 8

he told you no that is reason hes mechanic and you are not. if you had started with it then fine but there are some engines that do not need or want to use that for it messes engine up.

Answer 9

i would take that advice my uncle had a honda accord his mechanic told him to change oil he didn't do it his car died

Answer 10

synthetic is really expensive, and since it's not a performance engine, why would you waste the money?  Sounds like you have a good mechanic.

Answer 11

Ok. here we go. synthetic oils are very expensive and usually unless you start using them from day 1 in a new car ( less than 15,000 miles) the synthetic oils will have no benefit for your engine. If a motor is old it needs more lubrication from the thicker heavier oils available. like 10w-40. for your car i recommend 5w-30. good oil no heavy and will help will gas mileage.  

Answer 12

Because he is in with Big-Oil. There is no reason why you cant put fake oil in yor car. None I can think of.