Full Snythetic , versus Semi Synthetic, versus conventional LOFs

[Witsend]

Been running full synthetic oil and premium oil filters in my 3 personal family beaters, each with over a 100K. Used to set reminder stickers to 3 mo or 3k with conventional oil, 4mo or 5k with semi synthetic, or 6mo or 6k presently with the full synthetic. They all are pretty much short trip stop and go driven sh@t boxes and seem to go through at least a qt every 1000 miles , first qt low for Saturn SC-1gets is the 1qt of remaining full synthetic leftover from the 5 qt jug. The next thousand miles it would get a quart of whatever 5w-30 is on sale or left over from another 5 qt jug from another 4qt oil change. Actually I don't spend the money to top off the crankcase oil with full synthetic anymore whatever I find left over or on sale. Full Synthetic oil seems to be a total waste of money on cars you have to add a qt of it every thousand miles like wife's Saturn SC-1. People like her never check under the hood, so if you put 3mo or 3k on conventional and come in 2 and a half qts before the engine seizes ,that's better than it seizing up before it reaches the 6mo - 6k mark on a sticker for full synthetic.

[Joe Rappa]

I ran Synthetic 5W40 in my Cummins Diesel. 10k mile service interval. I'd grease the front end every 3k, not that it helped much. It still went through bal joints and axle joints. I drove it until it it 345,000 miles, and just sold it a week or two ago. It was strictly highway miles, and longer trips. Adjusted the valves every 100k, and never did a single engine repair on it. They're a pretty tough engine, so I have no proof that synthetic oil helped it at all. One thing I will credit the oil for was cold starts. I was winter camping with 3 other Cummins guys with the same trucks as me. At -36F mine was the only one to crank fast enough to start. We had to put some heat in the other truck batteries with jumper cables in order to get them going.
I run synthetics in all my bikes, and conventional oil in everything else.
Joe

[Witsend]

full synthetic definitely will flow better at sub zero temps, and engine can tolerate dangerously low crankcase oil levels and higher engine temperatures with borderline lubrication longer than conventional motor oil, so full synthetic in a 4 qt Saturn that only has 2qts of Synthetic left in the Crankcase after 2k is like only 1qt low with conventional oil I would hope. I ran Full Synthetic in my air cooled motorcycles too , but the water cooled V4 Hondas I often ran conventional Honda labeled oil, and used certain genuine honda automobile oil filters that had no other difference than being blue instead of black.Also being Old school it took me awhile to a accept that 5W-40 is a better choice for oil than 20W-50

[Witsend]

I wonder if a lot of repair shops prefer to keep customers on the conventional motor oil changes for 3 months/ 3k as long as possible instead of 6 months /6k for full synthetic oil, simply for the fact that the customer will have car back in the shop to check it over for other needed repairs sooner.
One other plus of conventional oil 3 mo 3k schedule is that some not too bright people that rarely check their oil level oil be down a good couple qts of oil, when they come in to change the oil at 4K , but if they figure sticker now says they can go 6K-10k they might be coming to your shop next visit 3 or 4 qts low with an engine knock at 6k.

[Crusty]

Most newer vehicles playing the GAME of "extended oil drain intervals", where, YOU TOO CAN ENJOY A LOW COST OF OWNERSHIP (LMFAO) by doing fewer oil changes and saving the planet too, are filling the crankcases with an extra quart or two or even three, of more costly "synthetic" oil.
So, with MORE oil each oil change, and the synthetic costing more, just where exactly are the "savings"-??
You are NOT "saving the planet" when due to extended oil drain intervals, the vehicle needs to be replaced more frequently. That also sure as bejeezus isn't saving you any money either......

JUST CHANGE THE OIL-!!!!

That means get it in, let your service provider take a look at things, do some of the other fluids, filters, cleaning & lubricating, that EVERY vehicle truly does need, in conjunction with the lowly "oil change".
By performing some of the other things that a vehicle needs, along with the "oil change", the I's are dotted, the T's are crossed, the vehicle stays in good, safe, reliable condition for many more years than the manufacturers want.
10, 15, and 20 years is very much achievable if the vehicle owner, and the service provider, are telling the vehicle what it gets, instead of waiting until the vehicle tells us.
Once the vehicle is telling us, we have no chance at controlling the cost factors. Waiting until the front end falls apart, or the brakes don't stop the vehicle at the next traffic light, or the engine doesn't start to get you home from the grocery store.....well, you got what you deserved..... A tow call and dinner is late. Getting to work tomorrow morning might be a problem.....

Just get it in and change the oil.

[Matt]

Oil doesn't wear out

I was always told that engine oil needs to be changed because it becomes contaminated with dirt, carbon, fuel, and metal. I agree that synthetic oil does a better job of lubricating but I feel it becomes contaminated at the same rate as conventional oil. Also, engines with small orifice hydraulic timing chain tensioners, don't tolerate sludge build up like an old small bock chevy would. Chevrolet's active fuel management lifters sure don't enjoy extended oil change periods. Here's what I've noticed with my customers, if you give them an inch they run it a mile longer. Once their oil life reminder comes up in the DIC it typically takes them another 1500 miles before they can stop their busy schedules and let me service it. Putting a lot of these cars at 9500 plus miles on an oil change. I suggest 3000 miles on premium conventional oil and filters and 5000 miles on premium synthetic oil and filters. I also service a lot of customers that drive on dusty dirt roads, which is not factored into the oil life monitor.

[Witsend]

Some cars , the oil just tends to get dirtier looking way sooner than other cars, whether it is PCV related, ring seal blow by, or engine crud deposits being cleaned off parts in suspension in the oil, and the oil looks bad by 3k anyway, no matter what is in it.
Whether it's a GM that you need to put a quart or more of dexcool in the reservoir every 3000 miles, or an Acura TL that's suffered a visit or two at hands of a GypsyNube ,there will be reasons to change the oil before the reminder light pops up.