Synthetic vs. Regular motor oil

I only run Mobil 1 on my GT3. Change interval is about every 5K miles.

Your actual change interval will depend on your driving conditions, but my motor alone costs something like $40K, so changing often is cheap insurance!

The cost of your motor has NOTHING to do with the type of oil that should be used. I have always used synthetic oil for all my cars from as far back I can remember and one oil change once a year. In fact my Audi prompts me at exact intervals when oil change is due and I blindly follow the ritual and have no problems with the engine. And, I wonder about the price of the engine on your car, is it 40 K, what is it, a Boeing 767 engine or what?

The trap is regular motorists thinking that expensive oil, whether synthetic, or top-name, is going to do anything to longetivise the life of their motor- it won,t- in fact can be harmful- UNLESS THE MOTOR IS DRIVEN REALLY HARD, as in race track- I use the cheapest 20w-50 oil I can find, change oil & filter together @ 10,000 km- my $200 car has done 688,000km , & is still not using oil.

The regular service interval as reccomended in the manufacturer's handbook for a VW Passat is 10,000 miles. This potentially messy job is entrusted to a local garage (trading name withheld) who have performed it without complaint over 7 years. The vehicle has reached 135,000 miles and looks like going on for at least another 50,000. Why worry?

I run synthetic in all my fast toys because it remains stable at higher temps. Conventional oils will burn leaving coke deposits on bearings. It is also what the manufacturers recommend generally. Were talking engines designed to live at their redline.

In my high mileage VW commuter I run regular dino oil. Everything has failed at least once on that thing except the engine! 180k miles and perfect compression running 15w-40.

That brings another point. Car manufactures are all recommending low viscosity oils now for increased MPG. If you want the best wear protection, run the highest recommended viscosity for your climate!

I'm quite a believer in synthetics, so long as the engine in question doesn't burn it or leave it on the road. I wouldn't know if they are suitable for vintage stuff but I changed to full-synth on a Yamaha FZR which, although a young engine, had a propensity for producing blue smoke on full tap. Changed to synthetic and never needed to top it up from then on. Never really explained this but I'd say use synth if your engine has a decent paper element filter and leave it there for some time (maybe twice the recommended interval).

This actually gets pretty interesting as you look further into this. If you read the article it states that changing your oil every 3000 miles causes more engine wear because engine wear actually decreases as oil ages. So every time you change your oil the wear rate is higher until the oil gets to a certain point. So if by using a synthetic I can stretch my oil change intervals out to 8 to 10,000 miles I can reduce my oil change wear rate by as much as 2/3's. use less oil, spend less time, waste less money. It's interesting that our european friends tend to change their oil at much higher mileage intervals with regular oil. Do they have a different mix or is it just us Americans wasting more oil? Why do manufactures recommend 3000 mile oil change intervals here in the states and much higher in Europe?

It depends on the manufacture. Many manufactures are switching to synthetics to stretch the change interval. Customers like having to do only one change per year versus three or four with conventional oil. Also, manufactures can assert better control and compliance on routine maintenance, which reduces their warranty claims and helps them validate those claims they do have.

Synthetic oil is really conventional oil, but the molecule chains are longer and the oil is engineered.

Another tidbit to consider; engines that have had conventional oils used in them for many years can and do experience seal and gasket leaks after switching to synthetic oil. I think the synthetic blends do a better job at removing engine sludge and dirt. These build up on the engine and the seals and gaskets. When accumulations are scrubbed out it many times provides a channel for synthetic oils to seep through worn seals and gaskets that were previously blocked by sludge. Removing the sludge is a good thing, but you may find it necessary to replace some seals or gaskets after the change.

Change intervals are rule of thumb. Most municipalities have their oils analyzed by an outside lab to tell them when to change the oil on vehicles in their service fleet. This saves them a lot of money and helps them schedule maintenance for vehicles early before problems become catastrophic. For us regular folks, the cost of changing the oil is relatively small, so regular intervals that err on the side of caution is not a big deal. I strongly feel that changing oil early is cheap insurance compared to the cost of some engines.

However, if you have a beater car that cost you $500, then who cares? If it starts to show signs of engine distress I would march to the nearest auto store and purchase every bottle with the word 'Miracle' on it and pour it in and keep driving.

Different crude will produce different oils. The reason for the development of synthetic oil was the ability to standardized on the properties. Back in the day Pennsoil was tauted as "good oil" because at that time Pa. crude had a better resistance to viscosity break down. Since todays engine designers encompass all sorts of other technology's, whose properties are linked together, one needs a very predictive lubricant. Synthetics are made from crude. What they do is separate out the chemical compounds from the crude, refine them, and then reassemble them. (the reason for the higher cost) Now the oil can be engineered in the engine system. The viscosity, its thermal conductivity (cooling capability), decomposition temperature and its sher strength are no longer variables. To answer your question, for standard driving using a factory built motor the Wall-mart cheepo will work fine. The key is the oils cleanliness. On a factory built engine 100,000 miles on the original oil is possible if it is keep clean. You guys on GIXERS use synthetics, remember the shear strength thing, that will help when slipping a clutch!

That just leads to the next puzzle what filter to use. Looking into this, there are great variances in oil filter construction. I guess if I choose to go synthetic with longer oil change intervals I should use a higher qulity filter. Here's a private report that cuts open and compares many of the common filters on the shelves. report.

Interesting and shocking. Interesting discourse on oil filters, shocked at my blind 'all filters are the same' or ' buy on price' philosophy. I think the fairly fastidious changing of filters which I have practised is probably a reasonable insurance against bad buying policy though, and the actual oil you buy still has to have a greater influence.

One could just about envisage a point in the future where manufacturers might delete the oil filter as a cost saving, there has been enough talk of sealed-for-life engines.