Re: Cobra 2.3L oil change question, first timer!
Ok so in conclusion my Volvo penta 10w40 full synthetic is perfect??
Arghh this is quite frustrating haha
Well, yes. (to both Q's)
BUT, Many people have a basic misunderstanding of the SAE's oil designation system.
For many years, automotive motor oils were (and for the most part still are) designated by a viscosity rating. Kinematic Viscosity IS a measurement of resistance to flow at a specific temperature. HTHS is the upper rating for an oil respecting shear at high temps.
SAE Viscosity Classes of Motor Oils according to SAE J300
Ideally,
you want an oil to flow at extremely low temps (well below freezing if you operate in those temps) and still have decent lubricating qualities at high temps (the engine, coolant AND oil fully
AT operating temp!!)
The oils of yesteryear, COULD NOT do BOTH! .................... SAE 30 & SAE 40 are literally GELLED at -35C for example.
It might be a semi liquid in the oil pump gears and actually produce a high pressure reading at your oil pressure gage, making you think everything is ok during start up....... BUT your rod, main, cam bearings AND your valve train are RUNNING with NO OIL because it cannot flow to those areas at that temp until it warms!!
So auto manufacturers recommended using an SAE 30 or 40 oil for summer use and an SAE 10 or 20 for winter use.
Some, who used 30 or 40 in the summer and did NOT change the oil for winter, saw catastrophic engine failures when it got cold enough to thicken the oil where it didn't flow.
If they ran 10w (winter) oil into the summer, they saw VERY low oil pressures in a hot engine in the summer and severely increased wear. (which wasn't very obvious)
In the 1950's, The industry developed VI-improvers that, when added to low viscosity oils, caused thickening as the oil reaches higher temps.......creating "Multi-grade" oils.
So in the case of "dino" (NON-syn) oils, if you use SAE10W-40, You ARE USING A 10W oil! .......... If you're using 15W-40 oil, you're using a 15W oil.
Those oils have Viscosity-Improvers added to thicken (or "stay" thick) at higher temps.
Those VI-improvers eventually break down. As they break down, the oil becomes thinner and thinner at those higher temps. (That's one reason to change it......in addition to getting "dirty") You change the oil long before this is allowed to happen (presumably)
Synthetic oils are QUITE different. A straight wt synthetic oil does NOT thicken at lower temps like a straight weight mineral oil.
Synthetics DO NOT use VI-improvers like straight wt oils so there's little or no degradation (like mineral oils) so they are able to perform (stay in grade) longer!
They DO however still get "dirty" with combustion products,condensed crankcase water etc and "dirt" that gets into the intake system through the air cleaner and past the piston rings.
The oil filters can trap some of it but not ALL of it! (
.....why you STILL need to change the oil!!)
You can read more if you like by going to the following links.
How Do You Choose the Right Type of Oil for Your Car?
If you REALLY want to get technical:
http://www.infineum.com/Documents/API/API Engine Oil Classifications 2010.pdf
There's more to read, just do a search. It's all over the internet.
I would suggest staying away from actual manufacturer sites like Chevron, Mobil, Am$oil, etc because their sites are mostly aimed at selling
you their products......
Going to sites like API, SAE, (since they don't sell anything directly to the public) can give you more objective info...............Lubrizol, etc. Although Lubrizol doesn't sell anything to the public they sell to Industry.....and they DO make most of the additives that go in many branded motor oils and motor fuels.
All the above "stuff" is argued DAILY, on every "motor" (auto, truck, boat, lawnmower, leaf blower, motorcycle, airplane etc) forum-site all over the internet.
A LOT of people use a particular (brand) oil and oil/fuel additive for emotional reasons.........
Examples:
Marvel Mystery oil (and other "Snake" oils) = My uncle, Dad, Brother, Pet Mechanic, Mercedes mechanic, Ford Mechanic, Mercruiser Mechanic......etc etc etc TOLD me I SHOULD use it!!! (really!!!! ............. they said you need to put mineral oil, Stoddard Solvent and LARD in your oil (or gas for that matter!!!)????:laugh:
Royal Purple = pleasing color, Chevron = well known name, Volvo Penta (Mercury, Yamaha, Evinrude, OMC, etc etc etc)= made my boat engine ............ Come on people, Do you REALLY think the those companies "MADE" those lubrication products?:facepalm:
Oh gawd!!! Here I go again! Another soap box rant! Somebody stop me!!!! (Bondo is laughing at me again!!!
)
Sorry guys!
Whew!
However, a trip to my local boat mechanic has taught me that omc is out of business and that I should use Volvo-penta brand oils and filters as a replacement. What I am unsure about is that he sold me 6 quarts of synthetic 10w-40 Volvo-penta brand oil and a filter of the same name. I brought him the manual which called for sae 30 but he insisted that the 10w-40 is what I need.
He says that Volvo-penta used to recommend the same but they changed the factory recommendation to 10w-40? Is this true? I mean the viscosity isn't even right. Should I just buy SAE 30 online? He didn't have any which leads me to believe he wanted to keep the sale.
That "dealer" is in the business to make money. They make money on that oil. That 10W-40 oil IS a synthetic and is fine. You're also just "fine going to Walmart, Oreillys, Autozone, etc and just buying Mobil 1 or any other synthetic. OR you can just use any brand SAE 30
For the Original Poster.
Just use what the manufacturer recommended back then or what they recommend NOW. you won't go wrong in either case.
ymmv......
Rick
