I think most of the above comments miss the mark. Synthetic is cheaper in the long run if you use it correctly. It doesn’t break down, coke, and sludge like non synthetic and thus can go for at least 12k before a change and for most conditions 15k between changes. The manufacturesrs who say you need to change oil every 5k have ulterior motives. I have been going 12-15k in everything from a Datsun 1200 in the 70s to a Hyundai Santa Fe and an F 150 currently and over thos 40+ years have not had one engine related issue, even well past 120k miles on the vehicles.
Aerodoc, not true at all. Synthetic oils will sludge just like regular oil in the right conditions. Ask some Saab owners. Although in that case they put the cat converter right under the oil pan, so the oil got fried ! Also ask the Mini owners who have followed a 15K service interval (per the manual) and now have expencive paper weights with 100-140,000 miles on them…
Test
Back in 1998 I bought a 1999 Dodge Durango SLT 5.9L. After about a year I started to expeariment with my oil change intervals. Here is what I found out. Check for oil level when the oil is cold and check for oil color when the oil is hot. After about 3000 miles when checking for oil level (cold) I noticed that I could not read the writing on the dip stick. When I checked the oil when it was hot (color) it was clear and clean looking. So I say to myself “self, why does everyone recommend to always check the oil when its cold”. Because it sells more oil changes and Click & Clack can go on vacation more often. I used this system for checking my oil and at 8453 I could no longer read the writing on the dip stick when the oil was hot. So I changed it. I use 10W30 Pennsoil. The owners manual says to change oil at 7500 miles so they are pretty close. I have used this system on my wifes 300 C Hemi also. At around 60000 miles the intake manifold plenum gasket on the Durango failed and sucked all the oil out of the pan and caused an engine knock (low on oil). I removed the engine and repaired it (rod & main bearings) and to my surprise the engine internals were as clean as could be!! I only drive the Durango in the winter (stored in the summer) and I live in MN. Anyhow thats my story and I am sticking to it!
AuggieFull synthetic does two things better than conventional oil. It lubricates better on extremely low temperature start ups. 2nd it breaks down due to extremely high temperatures less quickly.
So, if you live where winter temperatures are very cold a full synthetic makes sense.
If you drive a turbocharged motor your motor is running at extremely high temperatures and the turbo itself is running super hot. The bearing(s) in the turbo need good lubrication and full synthetic handles the heat and lubricates these bearings where conventional oil will not do the job after about 2000 miles post oil change.
Without these two situations, then conventional oil is just fine as long as it is changed every 5K miles of 6 months.
I do see though that almost all cam co. do not recommend syn. oil for flat tappet cam applacations?? Why is that??
Auggie@Aerodoc try 518,700 miles on conventional oil, that’s what I have on the original engine (never rebuilt) in my '88 Escort with oil changes averaging about every 5K miles and driven on dusty construction sites for the first 350K/12 years of it’s life and finally began using a small amount of oil at between 250-300K miles. Most synthetics say follow manufacturers oil change recommendation. There are a few synthetics that claim they will withstand higher mileage. What type synthetics were available in the '70’s? I wasn’t aware of any at that time. There are also many cars using synthetics and long OCI that have sludge problems. I’ve been driving about 36 years using conventional oil with several cars in the 200-250K mile range without an engine related issue. Not condoning or saying it would be good for the engine, but you could probably run on conventional oil 120K miles at 10K mile intervals on some engines without significant damage, but others would be a disaster. I still have about 20 cases of conventional oil in my garage that was bought when oil was cheap ($1 qt. or less) and about 50-60 filters I’ve bought at store closeouts at $1 each or less. My oil changes still only cost me about $5 each (4 quarts & filter). I can probably do 5+ oil changes and have 25K miles worth of clean oil for what 1 of your synthetic changes cost you even if you’re doing your own oil change. I’d much rather have fresh oil 5 times than 2 in 25K miles. I do have some Pennzoil Platinum in the garage that I bought several years ago when Pennzoil was running a $15 rebate promotion on a 5 quart jug which at the time only cost $20 so final cost was $1 per quart, but when I use it I plan to change the oil at it’s regular interval. Oil is cheaper than rebuilding engines.
I posted back on an earlier page of this very thread that I know people who use synthetic with 15,000 mile oil changes and their engines are a mess. My BIL is one of them. His dipstick is covered with thick, black varnish, and looking into the oil fill hole you can see it on the valve springs and everywhere else in there.
I know people who use synthetic with 15,000 mile oil changes and their engines are a mess. My BIL is one of them. His dipstick is covered with thick, black varnish, and looking into the oil fill hole you can see it on the valve springs and everywhere else in there.
When someone first changes from standard oils to synthetic they usually see what you are talking about. The synthetic oils tend to have higher detergent levels. You can't judge the condition of oil, by just looking at the color.
I would worry far more about how the car was serviced, including all the recommended services listed in the owner's manual than about what the oil looked like.Joseph, The engines I’m talking about were running synthetic with 15,000 mile changes since new. My BIL bought the car brand new, and when it had 3,000 miles on it, he replaced the original oil with synthetic. I’m not talking about dirty, black oil, but a thick, hard “crud” that has built up and cannot be removed, even on the dipstick. My Odyssey has run dino oil since new, and with 140,000 miles, the engine still looks and runs real well. There is none of the build up that I see in my BIL’s engine, and it uses no oil between changes, which I do at around 4,000 miles.
I for one don’t buy it. I believe he might tell you he changes oil every 15,000 but what you describe does not sound like it to me. That violates all experience including large numbers of cars in Europe who go more miles than that on synthetic. Feel free to believe it if you want; I do not.
Maybe the BIL does a lot of stop-and-go driving and short trips.
Don’t get me wrong however: it’s 5000 miles or 6 months for my car.
How did this thread get dug up?
For the record, my BIL uses his car quite a bit, and it does get very thoroughly warmed up. 15,000 mile oil/filter changes just don’t get rid of the dirt. For what it costs, I find my 4,000 mile routine works much better. Sometimes I let it go 5,000, but that is my limit.
If you do not test your oil, which is clearly a personal choice, you are guessing on this issue.
UNLESS you have it tested each and every time you have no idea if a 10,000 oil change interval is good or not. Testing every time is just plain foolish. Let us know when the car reaches 300k miles.
I have been going 12-15k in everything from a Datsun 1200 in the 70s to a Hyundai Santa Fe and an F 150 currently and over thos 40+ years have not had one engine related issue, even well past 120k miles on the vehicles.
WOOOWWWW…Really…120k miles.
Last vehicle I kept ONLY 120k miles was my junk GMC S-15. For the past 30 years we’ve been putting about 300k miles. Two of our vehicles went at least another 150k miles after we sold it…(still with original engines). I found out over Labor-Day weekend my 98 Pathfinder is still running. Daughter gave it to her Ex boyfriend…who then gave it to his younger brother who’s still in high-school. It’s now approaching 500k miles. When you start getting near 300k miles on a 12-15k oil change interval and it’s NOT burning any oil…let us know.
Full synthetic does two things better than conventional oil. It lubricates better on extremely low temperature start ups. 2nd it breaks down due to extremely high temperatures less quickly.So, if you live where winter temperatures are very cold a full synthetic makes sense.
I agree with that…but NOT the 12-15k oil change interval.
More reasons to avoid buying used cars. My Riviera had 530K on it when I traded. Original engine, never opened up, no oil usage. 3000 mile dino oil changes. I’ll be using Mobil 1 on my new car but changing at 5000 or 50% OLM. Really, 10,000, 15,000, 20,000 mile oil changes? Do you really want to buy one of these cars? So instead of doing a $30 oil change, you do a $25 oil test? Wow, I can’t believe such a cheap and easy maintenance item is such a controversy.
@MikeInNH ; I agree that testing the oil is the only way to accurately determine the condition and remaining life. I did this in the past with a small block Chevy V8. At 3000 miles of mixed driving, I had 60 ppm of metal wear, and the variation in viscosity, acid number, base number, and water & antifreezee were minimal.
Extrapolating this would give about 9000 miles before the metal wear would put the oil in the “condemn” level, according to EXXON’s labs. However, my driving had enough fast highway travel and in the winter I used an engine block heater. So very few really cold starts were experienced. Sludge was minimal in all cases.
Fleet managers test their oil every month or two on big rigs because coolant leaks or ingested silicon (sand/dust) could reach danger levels.
I currently change oil every 5000 miles which gives me a good safety margin to counteract abrasives and possible coolant leaks. In other words, sludge prevention is only one factor in the oil change interval. Mobil 1 Extended Service cannot prevent those other nasty things from getting into the oil.
This thread will likely go on endlessly.
Have to agree with Docnick,oil does so many things,extended oil changes are"pennywise and pound foolish"-Kevin