Continue to use Synthetic Oil??

[Jim Savage]

I know the subject has been covered in different degrees.

But if a car was born and raised on synthetic oil (Mobil synthetic since first oil change), is it OK to switch to conventional oil? Or is switching now a big no no?

1991 car has 70,000 miles.

Thanx,

Jim

[RickM]

You should be able to go back with no problem. In fact I believe you can even mix the two....not that it's a common practice.

[Bones]

Shouldn't be a problem , why change though?

[Jim Savage]

It's not my car but I think cost is the main factor. I would stay with the same oil but figured I would ask you gurus first.

Car is driven enough for a couple oil changes a year. Averaged out it's not that much of an expense for the payback of a long running car.

Thanx, Jim

[RickM]

"Averaged out it's not that much of an expense for the payback of a long running car."

I agree. If going to switch it may make more sense to go with Castrol Syntech on sale at Walmart.

[Jim Savage]

That's a good idea!
I'll give the suggestion to him and see what he thinks.

Jim

[widebody911]

I switched from synthetic back to dino in my 3.6. I have a chronic rocker shaft leak, and it leaks a lot less with the dino than the synth. Those who say synthetic does not leak more are welcome to come over and look at my engine.

[Don Plumley]

My neighbor was an engineer with Gurney racing, Nissan Motorsports (Indy, etc.), et al. From an environment where they tear down the motor after each race, he swears by M1 to the degree that he runs all his cars, even the 73 Chevy PU, on synthetic. His perspective is that especially at high temps, the synthetic does not break down and provides protection that is not matched by dino oils. His evidence is through motor tear downs where he says there was no wear - but before M1 there was visible wear.

As an unscientific aside, my son did a science fair project where we tested the viscosity of various oils after exposure to extreme heat. Considering a very unscientific method, data aside, the dino and blend oils looked visibly worse (sludgy) than M1.

YMMV

[avi8torny]

Your oil change intervals are greater with the syn. Cost is relative to changing to dino...maybe a few bucks more. Why change?

[RoninLB]

Originally posted by Don Plumley
he swears by M1
at high temps, the synthetic does not break down and provides protection that is not matched by dino oils. His evidence is through motor tear downs where he says there was no wear - but before M1 there was visible wear.

YMMV

I w/Don on this one...
the situation on 911 engines is upper piston temps/top ring.. M-1 has the highest ratings for this.. Dino stuff toasts.. different flavors of M-1 have different ratings in this area.. 15W-50 is the highest...........Ron

[RickM]

Thom: Mobil says that their synth won't create leaks. Which is a common myth. I would agree that a leak would get worse with synth.

Avi: I remember when experiments were done with longer synth oil change intervals (filters were changed) resulting in negligable wear.(I believe it was w/ Redline) However, Mobil 1 recommends the same change schedule as dino oil.

The heat tolerance is excellent with M1. But I can't help but recall when I had to add a quart of oil to a friends car in 5 degree weather(much colder w/ wind chill). The dino oil wouldn't come out of the bottle. It was that thick. The Synth pours with no problem.

[Don Plumley]

Originally posted by avi8torny
Your oil change intervals are greater with the syn. <...snip...>

Yes, you can extend the change interval. Buy why? In a relative sense: Oil = cheap; engine = expensive. Just my perspective.

[RickM]

Jim, I posted this link before. Perhaps your friend can read it.

Click on link....select "Why Synthetic"......select "What's it do for me" or "Myths about Synthetic oil"
http://www.mobil1.com/index.jsp

[Tom F2]

I haven't had leak problems with synthetic. I am using the Mobil 1 0W-40 "Euro blend," which makes my engine sound better. Also, I am getting around 21 mpg in mixed city/highway driving, which is better than I remember getting with the conventional oil. So, maybe the synthetic is a break even thing.

[Jim Savage]

Rick,

Thanx for all the help!! I will pass on the info.

Jim

[turbo6bar]

Anyone use synthetic on an engine that burns oil? My SC with rebuilt engine burns oil when I start it. It uses about 1 quart in 500 miles. That sounds like a lot to me. Those miles are light city driving, and trips less than 10 miles. I planned to stick with 20w50 or 15w40 diesel conventional oil at 3000 mile intervals, but I'm considering synthetic. However, I'm not crazy about spending $50 on oil every 3000 miles. I sound pretty crazy, eh?

Jurgen

[Bones]

All 911's puff a little smoke on start old or new. The 911 engine is air/oil cooled and so uses oil in the process my engine always needs a 'top up ' every 1000 miles about 1/2 litre usually that's after 140,000 miles .
I use Castrol Magnatec in my SC I think it's superb oil .

[sweater914]

so the debate continues

the synthetic oils be it Redline, Mobil, Amsoil in my case all do better at protecting engines, these oils will not break down at the extreme temperatures at the cylinder head and will flow at sub zero temperatures, you get what you pay for, Amsoil 0-30W is in the neighborhood of $8 a quart, but with a 30000 mile or one year oil change intreval with a filter change at 6 months, scary at first but it works, Amsoil guarantees a new engine if the engine eating itself is directly related to the breakdown of its oil

another consideration that most people forget is the oil filter, get the contaminates out of the oil!, your basic Fram can at the parts stores lets alot of the larger particles by only to tear up your engine, Amsoil (please folks, its the only oil company i've had any long standing experience with) offers a 1 micron oil bypass filter about the size of a coffee can, teflon is about 10 microns

my dad and i conducted an informal experiment switching to Castrol synthtec to see if it would be worth while to save a few bucks, in the '86 4 Runner you still had to do valve lash adjustments at least once a year, the inside of the valve cover using the Amsoil looked brand new shiny, after using the Castrol product the valve cover developed a dark brown varnish all over the valve train, we weren't impressed

the varnish build up from the dino oils does minimize the leaks at the expense of your engine, how does varnish form, the oil is breaking down

[ckelly]

Just a little note, Castrol has had charges brought against it with the FTC and NAD from Mobil 1 and Amsoil for false advertising. Castrol changed it's formula for Syntec (not synth blend) and is NOT a synthetic oil. I know it says fully synthetic on the bottle, but it's not, it IS pretroleum based.

"Recently, Mobil and Castrol went before the National Advertising Division of the Better Business Bureau. The NAD is a forum commonly used between marketers to resolve national advertising disputes, since it has a short time limit in which it must finish, it is a self-regulating body, non-binding, and avoids the far more serious FTC enforcements. Mobil claimed Castrol a) did not have the superior product that Castrol claimed and b) were misleading the public, since Castrol was using a hydroprocessed base oil in their synthetic oil product. The decision is at www.caru.org/nad99/0401.html "

"The outcome for part a) was that Castrol did not have the superior product that their advertising led consumers to believe and that they will have to modify their television advertising. These claims at issue were "superior engine protection" and "unique molecular bonding." "

"The outcome for part b) was that Castrol was allowed to continue to advertise their Castrol Syntec product as a synthetic oil formulation. The base oil used by Castrol met certain industry performance standards and due to the lack of a technical definition that differentiated between PAO and hydroprocessed base oils, they may continue. "

Castrol Syntec users, you've been duped!!!!!

I guess my point is, for the same money as the Castrol, you can buy a fully synthec Mobil 1 or for another buck or two a quart you can run the Amsoil, which IMHO is still superior, and change it half as often.

Just my .02 worth.

[RickM]

That's some good information on Syntec.

I was under the impression that synthetic oil could be produced from a petroleum or Vegetable base (typically corn).

I've been using Mobil1 most often as my friend owns a Mobil station. However, I was thinking of switching to the Castrol as it was even cheaper than what I get Mobil1 for.

I'll stick with the M1 for now.