Audi Junkie

To be clear, "synthetic" versions of oils are the same at operating temp as their dino counterparts. Outside of a technical forum, I see some odd assertions, this is one of them.

hahanson

Your statement makes no sense to me. What are you trying to convince us of? Same in what way? Please elaborate.

Summers22

iTrader: (2)

If you mean same viscosity, then yes. Same level of protection, then no.

hahanson

I would disagree with that, with the caveat that both engines have somewhat fresh oil as even at normal temps conventional oil breaks down faster than synthetic oil, so the level of protection offered by petroleum base oil changes sooner than synthetic base oil.

If he means they're similar in level of protection, I can't really say he is wrong. Perhaps in theory (in a lab) but not in application (real world use). Both flow similarly at normal temps (210-220F), and while the synthetic will actually run cooler than conventional the overall protection is similar -- but that's not really the point of synthetic oil.

It's the ends of the spectrum where it's far superior to conventional oil. It offers better protection as the temps go higher (towing, extreme city traffic, etc.), and it provides superior flow when temps go lower.

Why is that a big deal? Because the majority of engine wear occurs during cold starts. By the time the engine warms up to normal temperature where conventional oil offers similar protection, the wear has already occurred. Over time and miles it eventually becomes significant.

Martian

As a reminder.

BadFish523

I just want to throw this out there. I had my timing done about 200 miles ago and am going to change the oil a little before 500 just in case any dirt got in while the timing was done. This thread is mostly about what weight oil to use but I want an opinion on brand. I'm leaning towards going with Mobil1 high mileage full syn 5-20. Any opinions on this brand?

Mulestang

That's what I'm using in my 110k mile 5.4.L. While I've done no oil analysis to support it being any better than other oils, I run it because it's a quality oil at a very affordable price. My life is complicated enough. I don't need to worry about motor oil.

hahanson

5W-20 is a good choice. I use Mobil 1 almost exclusively, but that's more personal choice than anything backed by scientific data. I've also used Valvoline, Pennziol, Amsoil, and Shell Rotella (all full synthetics) at various times with no issues whatsoever. I don't mind any of those alternatives if I find them on sale, but generally speaking Mobil 1. It's doesn't cost much more than conventional when you buy it in 5 Qt jugs (Walmart regular price is like $25 -- $5 per quart). I use Rotella exclusively on my wife's R6 as it's great with wet clutches. Mobil 1 race for my CBR. Keep in mind that getting a GOOD oil filter with anti-drain valve may be more important than the brand of oil.

I'm not sure "high-mileage" versions are any better, unless you have some gaskets seeping (reportedly they contain more "conditioning" additives for seals/gaskets). In addition to these seal conditioners, high-mileage oils usually claim more detergents designed to clean out sludge inside the engine, plus other additives meant to reduce wear on moving parts. Every oil, though, makes similar claims. If you've used good oil previously and kept reasonable OCI, it should be clean anyway.

Couldn't hurt if it costs the same, but I wouldn't pay extra for it. Seems just another oil company marketing ploy to get more $$$ from consumers, but that's just my opinion.

BadFish523

Yeah the high mileage is the exact same price as the regular Mobil1 syn. I just kind of figured it wouldn't hurt to give some of the older seals a little conditioning. Even though I just had my timing done so I'm not really sure there are any old seals left affected by the oil but hey for the same price. My mechanic recommended Mobil1 but I'm just looking for everyone's opinion on it. Keep them coming all!

hahanson

Really trying to make this thread go farther south, eh?

In theory some brands may be better than others, but in application they all pretty much do what they're supposed to do as long as you follow the viscosity and standards recommended by the manufacturer:

SAE 5W-20 engine oil is recommended.

Only use oils “Certified For Gasoline Engines” by the American
Petroleum Institute (API). Use Motorcraft or an equivalent oil meeting
Ford specification WSS-M2C153–H. SAE 5W-20 oil provides optimum
fuel economy and durability performance meeting all
requirements for your vehicle’s engine.

While there is plenty of evidence PAO based synthetics (Group IV) are better than Petroleum based synthetics (Group III) which is better than conventional, beyond that there are no "independent tests" I've run across that definitively crowns one brand of oil over another, manufacturer's claims not withstanding. What you will find is plenty of anecdotal evidence and personal preferences.