Jewcano

iTrader: (4)

Ok heres my story. Im nearing the 5K mark since my last oil change, however im running on synthetic, which is why im driving this long without a change. I suggested to my father today why not get my oil changed. Now he's knowledgeable about cars, because he used to work with them in Russia and stuff, but im kinda iffy on his opinion on what i should do. He suggests that i can still drive at least for another 2-4K miles with the same oil, which would mean im running around 9-10K since last change. I personally dont think this is a good idea, but he suggests that its fine. Whats ya'lls opinion on the matter?

Also as a side note, he said when changing oil its not bad to use kerosine somewhat like seafoam, in the fact that you put it in your crankcase, but heres the thing, you disable the ignitor, just so the oil pump would circulate the kerosine and help clean out your engine. He said to do this after you remove the oil. He's done it before and said it had good results, anyone ever heard of that either?

Tammy

I would recommend you change the oil at the recommended 5,000 mile intervals ... or every three or four months, regardless of the oil type or brand.

The engine oil cleans, cools and lubricates the engine. It absorbs corrosive acids and combustion by-products. And fine sand and grit that passes by the air filter.

Your dad's referring to the cleaning of a "cast iron block and head" engine with kerosine. This was a common practice when any non-detergent 30 weight oil was used for an oil change, prior to synthetics and today's detergent oils

But, with today's aluminum block and head engines, not really a good idea. Any kerosine residual will mix with the new oil, causing it to breakdown.
You may start an oil seal leak on your engine, or worse, valve stem seal failures.

Most respectfully to your father's idea, it's a wee bit out of date.

Be sure to use a good quality oil filter with your change.

Jewcano

iTrader: (4)

Thank you for the reply.

JohnEd

iTrader: (1)

I picked up my cherry 93 SC400 a month ago. It needed an oil change when I got it but the paper work said it was on 2.5K old regular. I wanted to start off right so I added 4 quarts of diesel to a warmed engine. Over full it gets to splash around in ther and clean things up. I drained what looked like TAR out of the engine. Glad I did that or my fill of fresh oil would have had exausted detergents in few miles. I have done this at every oil change on every car I have owned since my new 65 VW Variant. Doing all of my own work I was into all of my engines to adj. valves or just to "look around". They have all been pristine. When I checked the SC400 last week while measuring the valve lash it had varnish deposits in a couple of different layers in the head and a particularly clean swipe opposite all of the lobes. I have never had any problem with any of my alu. heads that I could attribute to the flush.

Your caution is NOT falling on deaf ears, however. I'm sure Lexus would vote no. I will try some others for an expert opinion. And yes, I am "old school" and 64 years old.

Play safe and be happy.

JohnEd

wildrice09

For you I would definately change it every 5k since your running synthetic. Don't let it go over 6k at the most. I'm using regular 10W30 in my car and I change it every 3k miles pretty precisely. Plus if you run the car on old oil you sacrifice gas mileage since the motors working harder.

AutoCoutureSC

iTrader: (8)

did i read that right? could you explain more to me on how that works out in our cars? I'm just confused...

Jewcano

iTrader: (4)

Yeah, i too would like to know the benefits of diesel in a gas motor?

TunedRX300

Actually Oil Change Interval (OCI) and the subject of mineral vs synthetic always spark debate. That said, I think it is best to give you scientific data and let you decide what is comfortable for you.
In this study, it is interesting to find out that engine wear rate actually decreases when one let oil age past 3000 miles. There is even a SAE paper to support this

In the attached graph, you will find dotted lines, which are rate of engine wear in PPM, decrease when oil stay in the engine >3K. Solid lines are cumulative metal particles, of course, increase with oil miles.
http://neptune.spacebears.com/cars/s...il1.html#topup
But extended OCI is not for everyone, some will lose sleep and must be compelled to change oil @ 3K but others are perfectly fine leaving the oil for 10K, saving some $ and used oil for recycling.

shaloo

You say it is better not to change oil every 3K miles and that we that do, may be doing our engines some harm. Is this because the oil is drained, and when we start it, there is 3-4 seconds of no oil pressure until the filter is filled and the oil passages refilled with oil. If we had a pre-oiler to pressurize the system after changing the oil and before starting the engine, then would we be ok??

TunedRX300

I don't believe the engine is "harmed" to the extension that it will break down shortly, just more wears. The graph is an empirical measurement of metal particles found in the oil as it ages. If you believe the test method, then fastest rate of engine wear occurs in the first 3K miles. Now there are people who could care less how many iron/copper/lead ppm, they have done 3K change interval for X cars or X miles and reported no problems. That is fine, it is an individual's decision.
I believe one of the main reasons for faster engine wear < 3K miles is the oil filter. It needs to put on a few miles to reach maximum filteration effeciency in order to retain as many harmful foreign particles as possbile. Microscopic "pores" on the filter material get plugged up by these foreign particles as the oil filter put up a few miles. Of course one does not want oil filter to 100% clogged since all oil will be bypassed. But changing it too often will reset this "settling" effect: just when the oil filter began to do its best work, it get changed.

T0ked

iTrader: (2)

Longer oil change intervals are not dangerous for the engine as long as you use proper oil and the engine itself is in good working order. A good synthetic oil will last longer than a dino one. If you regularly do 3k mile or 3 month OCI, then there is really no real benefit of synthetic (debates debates). The reall benefit of synthetic comes with longer lasting with good protection. The danger comes when the additive package in the oil runs out such as calcium, moly, zinc, etc. The best way to do this is to do a used oil analysis. You send a small sample of your used oil and they send you a report with what they found in the oil (metals, fuel, coolant, etc) and they also report how much of an additive package is left in the oil. This is the only safe way to switch to long OCI. M1, castrol Syntec (GC, BC), red line, and some of the rarer boutique oils seem to do really well. I change my oil twice a year and go about 5k-6k miles each time. My UOA comes back clean and the company states I have much more life left in the oil.

People use diesel oil and even tranny oil in the crankcase to clean it. This was common practice back in the day since those oils usually had more detergents than motor oil. But modern motor oils have as much or more detergents and additive packages making that not as benficial, but still no harm in doing it. Many of the esther based oil will clean your engine as you drive also (Mobil1, german castrol, belgian castrol, red line, royal purple).

T0ked

iTrader: (2)

I don't know much about the results of that graph. But I will say that a good filter is imperative when going to longer oil change intervals. I use mobil1 filters. They have been proven to have excellent filtering properties and seem to do really well on longer OCIs. For the very reason TunedRX300 mentions, some people fill their filter with oil the day before or even before the oil change. This allows the filter membrane to be primed and also reduces the interval between that first crank and build up of pressure as the filter fills. Pre-oilers have been used in high hp race cars for this very reason also. also oil pressurizers where an extra quart of oil is pushed into the engine prior to first crank.

All good for high power engines, but I think overkill for a stock car. I would fill the filter with oil, but the mess it makes as I shimmy it around the engine bay to get it on is not worth it.

Jewcano

iTrader: (4)

Wow i got more responses in this thread than i thought. I do really appreciate ya'lls input. I am nearing the 5K mark since last oil change and will not go above 6K. Thanks for the info guys