A&Q about 350Z
Q:
Hey everyone, i have a 4.6L V8 ford tbird, that has 127,000 Miles. The engine is fine, no problems, and doesn't eat any oil.
I just changed my oil with recomended 5W30 oil. It is regular engine oil, Quaker State is the brand.
Should i be using Synthetic..?? What the differance in using regular 5w30 and synthetic..?
Is quaker state decent, my bud with an 00 Maxima uses it, he told me that all he used on his cars.
Also, should i be using high mileage, or is that just a gimmick.
A:
The high-mileage oil is a gimmick. The difference between regular and synthetic is where its made. Regular oil comes from dead dinosaurs and is refined from crude. Some scientist figured out that its not very difficult to reproduce that molecule in a lab, and that's where synthetic comes from. They are the same oil molecule, its just that "dino" oil isn't perfect. There are carbons, parafins, impurities, etc that can't be refined out. It doesn't affect the operation of the oil in the engine, but since it already has stuff in it, it can't dissolve as much.
Synthetics start pure, so they can dissolve more (both initial additive package and junk from the engine) before they start failing and losing their lubrication qualities.
Both regular and synthetic lubricate equally. One is not "slipperier" than the other, but synthetics are a purer oil.
Typically, the fact that synthetics will dissolve more junk can make older engines leak oil. the old seals and gaskets can crack, then they fill with gunk from the engine. Usually they seep a little oil, but sometimes when you put synthetic in, it cleans the gunk so well that what once was a seep can become a full-on leak. If you notice leaks with synthetic, usually a bottle of stop-leak will help.
There were a couple threads here earlier that spoke specifically about Mobil 1 synthetic in the 5w30 variety seeming very thin and not offering enough oil pressure. Not sure if any of it was figured out, but often times engines that call for 5w30 are fine with 10w30; definitely in the summer, and even more so with 127,000 miles. I used to do 5 in the winter and 10 summer, but I've found at 88k miles, my LT1 doesn't make enough pressure with the 5. Just a thought.
A:
Well, it's not a gimmick, but it probably would be a waste of money on you engine.
Synthetics are better in almost every way, but not much that you would notice on a street engine.
And a couple of urban legends: "Synthetics cause leaks"
A couple things led to this legend. In the early days of synthetics, the matierial used didn't provide some of the swelling in cork gaskets that dino oil did, so they COULD cause leaks. New gasket materials and additives to the synthetics stopped this. One remaining caviate... Synthetics typically have a greater "pour" rate at ambient temps. So if you have an engine that drips in the driveway now and you convert to synthetic, it MIGHT drip a bit more.
Synthetics are "slipperier", especially at lower temps. And they stay together far better at high temps.
However, unless you do a lot of very cold starts and/or operate at very high oil temps (275+), you will never see a return on your investment using synthetics. They are better in every way, but it's like buying a 30ghz PC to do Word processing.... <g>
BTW, Doing dyno tests here using the same weight oils (and viscosity indexes) a synthetic based oil provided up to 3% more HP with oil temps below ~140 degrees. At above that point we saw nothing. On the chassis dyno when testing synthetics vs. crude in the gear box, showed even greater gains at low temps.
Jim
SR Racing