I have always put 10w-40 on my car (last two oil changes) and just now I read some tag in the engine bay that vaguely reads Only use 0w-30 oil. My guess is that its 10w-30. So what is the actual difference between the oils. Will my car run better if I get the 10w-30?
30w is thinner and will flow more easily in cold weather. That's really the only difference. Older engines need a thicker oil to compensate for worh rings and looser bearing clearances...
i usually use 10-40 here in az because of the heat. i doubt it'll make any difference at all in how it runs.
The first number is a rating of how the oil flows cold... The second is how it flows hot... So 10w40 flows as 10 weight oil cold, but 40 weight hot. 10w30 will flow the same cold, but thinner when hot. I look at it this way: Most of your engine wear occurs at start up... so you want the oil thin at start. That way it will flow quickly. Mobil1 has a 0w40 that makes me feel warm and fuzzy about quick oil flow and then good viscosity when hot. Just a thought... Dave
what about that oil that supposedly gives you all the horsepower and stuff (its called Q I think)? Is that true or is that all just crap?
Mostly crap... One way to make power with oil: Thinner oil makes more power, just because it is thinner and causes less parasitic loss. The trade off is thinner oil has less cushion for parts during hard running. There are some things out there that are good IMO, but there is far more 'snake oil'.
I watched a Harley gain 4 HP from an oil change. It was on a friend's dyno, the bike, (a race bike) ran w/ regular oil, then switched to the synth. racing oil, and VIOLA! 4 HP gain, in about 20 minutes. No dyno tricks, no reprograming, same day, same time, same atmospheric pressure. He wasn't trying to sell oil, the bike, or the dyno. He had no dog in the fight, he was just as curious as I was. YMMV
I run what the owners manual says to run... 10w30 in the winter and 20w40 in June/July/August. The heavier oil seems to help keep the oil pressure up on those really hot days in stop and go traffic. The engine has had only Castrol since about 1976, and that's what I continue to run in it. My dad runs 20w50 Castrol in his '95 Mustang GT year round..
Regardless of what brand oil of what ever weight I run.....I will still use the "Risolene" oil treatment
Synthetic oil and teflon are the 2 things I don't consider snake oil. I believe they are both at least good for less wear. Power gain is argueable, while possible I suppose. The biggest gain though is changing the weight of the oil. Thinner oil takes less HP to pump. Now as for 4 hp on a dyno, I find gains that small hard to swallow. Any competent dyno operator will tell you that they have a margin of error of between 5 and 10 hp per run. Not that he didn't gain... It's just that for a gain that small to be credible, you would have to make about 5 runs before the mod and 5 runs after, then use the averages to prove a gain that small.
I'm a firm believer in synthetics. Living proof the stuff works. I want bore you with the long story so heres the short version. Had a vibration at 50 mph so I speed up to 70 mph to see if it would get better. It only got worse. About 5 miles down the road I decided to pull over and check out the truck. Found only dust on the dip stick. Filled engine with oil, started the truck and drove it until the company decided to get me another one. We had treated the company fleet with synthetics before this happened. As far as horsepower gains I BELIEVE this to be true also. Ratio411, 4 HP on a Harley is a big gain. Mustang and Fords Magazine just performed this conventional/synthetic oil change test with 8 HP gain and 22 Lbs. torque Ken
The dyno was probably much more calibrated and accurate then some car dynos. I used to be in Kart Racing, and engine builders would dyno engines after every rebuild. A 5-10 hp margin of error with engines that were only makeing 8-12 hp would render the dyno pretty much useless, and a 4 hp gain would be HUGE. Things work alot diffrent when working with smaller engines.
