Will the grade of the oil I put into the car affect the performance. For example, If I use SAE 20-50 vs. using 10-40 vs. 5-30. Will my car be slower if I use thicker oil??? I ask cause when I got my oil change last time, they used 20-50. THey did it without my knowledge until I saw the sticker. The car ran fine so I wasnt too worried. Then I recently got a change and I used 10-40 and it seemed like it pulled a little better. Can it be the oil???

 

It will definitely make a difference. A synthetic 0W-30 or 5W-30 will be your best bet. If you live down south a 10W-30 is okay too. Anything else shouldn't be used.

These weights will be different if you choose conventional oil.

 

Be careful with that advice. A worn/high mileage engine should not use synthetic oil. I would say if its high mileage go with conventional motor oil. There's an oil comparison spreadsheet around that is supposedly very informational.

 

If the engine has been neglected and is high mileage I would agree. If the engine has been well maintained and high mileage, it is safe. Reference the BMW 528 that was switched to synthetic at 143K and now has almost 200K on it. (It's in the spreadsheet)

Besides, to answer his original question, the different viscosities in the oils he was using would affect the performance of the car.

 

Bull.... It might be wasting money but it absolutely will not hurt anything....

-RMB

 

My engine has about 130K on it. I use conventional oil normally, Castrol GTX 10-40. I live in southern californail. I bought the car used and have no idea how well the previous owner took care of it. It seems like its in great shape though. I use 10-40 in the summer and during the winter, I use 5-30. Is that correct or have I had it backwards for the past 2 years??? I dont think it really matters since I do live in sourthern california. But I tried snthetic for a while and thought that since its already been using conventional oil for the majority of its life, Ill just continue using it. Thanks for the help guys.

 

Your correct that it wont hurt anything, but I don't know about you but I don't feel like having my car lose oil because it leaks through the seals.

 

Aren't synthetics better at higher RPM's, and don't they also have better additive packages? I've always been under the impression that synthetic is better because it the package breaks down slower. Why does the mileage make a difference?

 

There's very little chance the seals will leak if the car has been properly maintained. Just because the car has high mileage does not mean the seals will leak. They leak because an engine that has been neglected will start to form sludge. That sludge, if it builds up around the seal, causes problems. There are properties to an oil that promote seal swell. If the oil can't get by the sludge the seal will tend to dry and start to crack. It doesn't leak because the sludge forms a false seal. If you introduce synthetic into a neglected system, this sludge will be cleaned away, exposing the damaged seal, which will then leak. Sometimes the oil will resoak into the seal and cause enough swell to stop the leak, but the odds aren't in favor of that.

I've seen engines that have been neglected and abused try to use synthetic at 45K and leak. There are also engines with well over 100K that switch with no problems. I believe Karguy switched on of his Maxima's around 130K.

 

There are many reasons why a synthetic is superior. One of them, as mentioned, is the additive package. The additive package is responsible for acid neutralization, detergency/dispersancy and anti-wear protection among other things.

Another major difference is the basestock of the oil itself. A synthetic basestock is more resistant to change with temperature. Thismakes starts easier and the engine is protected faster when it's cold. The oil also maintains viscosity under much higher temperatures in order to continue providing protection under high heat/high load, such as hi rpm. A conventional oil will thin out rapidly under high heat, leaving the engine not as well protected. If continually exposed to high heat, a conventional oil will start to evaporate and thicken out of it's viscosity grade. What was once a a 5W-30 can turn into a 10W-30 very quickly.

For more information about viscosity, oil and it's properties, I've put together a pretty good collection of articles on my website.

On the Org, Bill's spreadsheet is also very informative. It can be found in the general forum.

 

For all you lazy guys (like me) who don't want to change the oil themselves, I think WalMart is the best place to have it changed. You can get a synthetic oil change for like $26. Just wanted to share that.

 

Yeah, but just be aware the SuperTech is a Group III basestock (cheap) and at least in the 5W-30, at the very bottom of the allowable range. It does not appear to hold up very well. It's rumored that it's a derivative of Quaker State, though no one's sure yet.

You do get what you pay for.

 

i use mobile 1 synthetic 5w-30

 

You need to use the 5W-30 if that is what the manual recommends. Reason being is that the engine bearing tolerances are made extra tight these days in order to get better performance and gas mileage, and a lighter weight oil (5W-30 vs. 10W-40) is required. I can't remember seeing any car within the last 10 or 15 years that recommended using 10W-40 or 20W-50 except in extreme conditions (desert, etc.)

 

the manual does say to use 5w-30 but i asked around and people told me to use 10w-30, so i have been using pennzoil 10w-30 since i had the car, should i make a switch back to 5w-30, is there any difference if i leave it

BTW i live in new york with varying climates

thanks for any who answer my stupid question

 

It's not a stupid question. I did the same thing with my last car and I really felt a difference in performance, so I switched it back. I think they recommended 5W-30 and I went with 20W-50 for the summer and the motor definitely was slower. I wouldn't go paranoid over it, it's probably ok to have 10W-30 in it while it's hot outside, but I would change back to 5W-30 before winter and leave it that way from now on. Just my two cents.

 

In NY with conventional oil, use 5W-30 for the winter and 10W-30 for the summer. A conventional 10W-30 is too thick at start-up during winter and is very hard to pump to the top end of the engine. With a 5W-30, the car will crank easier, reducing drain on the battery and the oil will flow faster for better protection. You will also see an increase in fuel economy.