Thread: Sythetic VS Regular 5W30

Originally Posted by SlowM90

Okay...Im soooo confused!!! Someone PLEASE clarify this! I was always told..the thicker the oil.. as in 10w-30 the better for colder area..as in up North...Not only was I told this but reading around I noticed almost everyone from up North runs 10W-30! And you would think you would want a thicker oil in the winter...not the summer. I have read up on this after reading this forum and some say heavier is better in the winter and some say noo its needed for the summer..So someone who knows can you please clarify this!

I looked around a couple sites and lifted this for you.

Most oils on the shelves today are "Multigrades", which simply means that the oil falls into 2 viscosity grades (i.e. 10w-40 etc)
Multigrades were first developed some 50 years ago to avoid the old routine of using a thinner oil in winter and a thicker oil in summer.
In a 10w-40 for example the 10w bit (W = winter, not weight or watt or anything else for that matter) simply means that the oil must have a certain maximum viscosity/flow at low temperature. The lower the "W" number the better the oils cold temperature/cold start performance.
The 40 in a 10w-40 simply means that the oil must fall within certain viscosity limits at 100 degC. This is a fixed limit and all oils that end in 40 must achieve these limits. Once again the lower the number the thinner the oil, a 30 oil is thinner than a 40 oil at 100 degC etc.

And just because this thread is really getting fun, I’ll throw my hat in the ring.

Castrol SYNTEC = driving in extreme climates (frigid winters/scorching summers)
Castrol GTX = driving in moderate climates
Redline = racers

us people up north change seasonably.........5w for winter and 10w for summer. This is done so that in the winter you have thinner oil at start up, thus supplying proper lubrication when the motor is started(most critical time) and once it warms up 5w and 10w do the exact same thing. So you want thinner in the cold so that it gets to where it is supposed to sooner and easier.

As this thread clearly demonstrates, engine oil is a mysterious and passionate subject for car lovers like ourselves.

Now I feel I must tell a story or two. I had a P.O.S. Ford as a teenager that called for 10W40. Well, in the winter on the really cold Wisconsin mornings the thing would hardly ever start. Until I changed to 5W30, as the family mechanic suggested, then my cold starting issues were essentially fixed. I couldn’t believe it back then, but lesson learned.

My second story is on Mobil oil. I bought a brand new car as I left the military in 95, the first oil change was my tried and true Castrol GTX. The engine was clean as a whistle and ran like a top. But then there was (and still is) a huge buzz on Mobil 1. But being in college I had no money for synthetic oil, so I got some regular Mobil 5W-30. Well, the first thing I noticed (after about two weeks) was an extremely coherent layer of micro varnish on every piece of metal I could see exposed to engine oil. Even the dip stick had it, and it would not come off! But the car ran fine until that faithful cold winter morning. I as the car started it let out a deathly screech like I have never heard before. It scared the crap out of me, my new car! Needless to say, that Mobil oil came out ASAP. And btw, that varnish never did come off completely. To this day, I wouldn’t put Mobil in my car if it was free.

PS. As I wrote this, we just got our first snow fall.

It has been snowing here all morning. I have almost an inch on my car right now. I have also heard numerous horror stories related to mobil 1 synthetic, and would never use it in any of my vehicles. Also, synthetics help to cool motors easier than standard oils do, so if you are having problems with cooling, it can help some. On our off road race team, the first year we had our truck, we were running conventional oils and were overheating the oil, we switched to synthetic oil, and the oil temps actually dropped 40 degrees when compared to the standard oil. Even if your engine coolant is running at normal temps, if you are running your motor hard, your oil temps can be well above the coolant temp. If you are running synthetic oils, this is more resistant to breakdown at high temps, and it will run cooler as well.

There's no reason to switch to 10w-30 in the summer if you're running 5w-30 in the winter. 5w-30 will behave just fine in the summer too...

Originally Posted by Sabrewings

There's no reason to switch to 10w-30 in the summer if you're running 5w-30 in the winter. 5w-30 will behave just fine in the summer too...

Unless you're running really crappy oil.

i switched to thicker oil because my oil pressure went to the ****ter.

I use 5w-30 amsoil all year round.

[/QUOTE]To be fair, most professional racers do not use any off the shelf oils, including synthetic. Normal every day automotive oil is not intended for those conditions. So calling out one brand because it doesn't work properly in conditions it wasn't designed for is a little outside reason.[/QUOTE]

Royal purple claims to be high performance. Brad Penn Grade 1 is high performance yet one works fine in race engine and the other doesn't why is that? Royal purple has a Race oil line and it doesn't work any better than its off the shelf brother.

Castrol SYNTEC = driving in extreme climates (frigid winters/scorching summers)
Castrol GTX = driving in moderate climates
Redline = racers

I'm thinking about trying that redline oil in my SBC there has been alot more guys running it in there alcohol motors. Its fresh this year and its cheap to rebuild if it doesn't work and its easier to get. I have to order Brad Penn oil and I hate having to have two cases on hand at all times because both motors take different oil.

I run 10w30 year around I probably should run 5w30 but I hate switching. My oil cap says 10w30 so I guess that's what I'll run. It seems like it can go from -30 to 100 in the same day in South Dakota, two weeks ago it was 70 and now there's snow on the ground.

but it is quaker state....I personally run amsoil year round as well.

I ran RP in my car for about 7 to 8 months, spun a bearing after a cam install and the inside of the motor was nasty. sludge on everything but I dont think this was from the RP I dont think the previous owner changed the oil very often. Still i Havent gone back to it but may someday if i can find it cheaper around here. Or might go with Amsoil who knows.

Originally Posted by 94prixer

You dont have to, but like they said it flows different until it heats up, which would be thicker until it does.

In the summer, when your oil is sitting about 80*F on a "cold" start, they both flow the same. It's when you get to cold temps that they're different, so why bother changing from 5w-30?

Originally Posted by Sabrewings

It's not going to detect a problem like your air filter. It has no sensors or anything of that sort. It simply measures engine load, engine temps, RPMs, mileage, etc to determine when the oil should be changed. If your air filter is messed up that's your own fault.

It also assumes you're running dino oil so for synthetic users when it goes off you could most likely go longer. The OLM is no replacement for real analysis though.



To be fair, most professional racers do not use any off the shelf oils, including synthetic. Normal every day automotive oil is not intended for those conditions. So calling out one brand because it doesn't work properly in conditions it wasn't designed for is a little outside reason.

I never said it DIC used your airfilter for estimating how much time you have left on your oil. I used that as an example of why an oil analysis report is nice to have done, because I probably would not have caught that until I cleaned my air filter. I own a DHP powertuner and I can purposely mess around with the oil life system by throwing off my tune. GM just used the oil monitoring system for normal dino oil and never designed it for synthetic. Lets not also forget oil technology has changed in the last 12 years since my GTP came off the showroom floor.

Originally Posted by flash527

ive always ran full synthetic, but keep this in mind... once you put synthetic in your car, you can NEVER go back to regular oil.

This is absolute bs if I've ever read it...you are very misinformed. If you have a higher mileage motor that leaks some oild, you don't want to switch to synthetic or it can leak worse. Other then that you can switch back and fourth whenever you want without any issues.