Why is M1 not good during the "break in period"?

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Jul 9, 2004
M1 comes in many new high performance, but it seems to be the consensus to wait between 2k and 5k miles before switching to M1 on most passenger cars.

Why is M1 so highly regarded yet isn't recommended by many in brand new engines?
Many new engines come with special break-in oil. If the owners manual doesn't specifically say to keep the break-in oil, M1 is fine as a first fill.
Do a search on break in. I believe that is an old myth. Cars today don't need an elaborate break in. For my next car I will change to a synthetic around 2k miles. I won't gun the car off the line but will do several strong accelaration runs from like 30 mph to 60mph. I think this is a good way to get the rings to seat properly. I could probably switch much earlier, like around 500 miles if I wanted to.

Originally posted by buster:
I believe that is an old myth. Cars today don't need an elaborate break in.

My last UOA from Blackstone useing Castrol Syntec 10/30 they recomended I change it at 3000 due to the wear metals.They said it is still breaking in and it had 6000 miles. So I put the same oil in again to see at 3000 if the wear #ers come down then I will go to AMSOIL 10/30, or Synergyn 3/30.

some cars come with mobil 1 in the engine from the factory (vettes, porches, mustang something or other).

i know that some porsches come broken in, so that could explain why they include it from the factory.
Your best bet is to just go with what the manufacturer tells you. IF no stipulations are made in the owner's manual (be sure and ask the dealer too)change the break in oil as soon as you want with whatever you want. If you're told to leave the break in oil for a certain period or not to use synthetic for a certain period, then follow those instructions and begin using syn after the specified time. When I say ask the dealer, I mean the service dept, not a salesperson unless it is clear he/she is a well-informed motorhead. Seotaji is probably on the right track with Porsche...I believe they do run in their motors before final vehicle assembly and the others (Corvette, Aston Martin, Viper, AMG, I believe, etc) may have special procedures as well.

Originally posted by 05corollaLE:
M1 comes in many new high performance, but it seems to be the consensus to wait between 2k and 5k miles before switching to M1 on most passenger cars.

In regards to the afforementioned Honda recommendation...I wouldn't sweat it. I waited all the way until 738 miles to change the factory fill, then again at 2500 miles, then finally put in M1 at the 4K point. Our Honda-powered Vue is wearing in quite nicely...guess I blew that recommendation out of the water. I just don't buy Honda's recommendation after seeing the UOA data on the factory fill. Plain & simple, it doesn't add up.

I wanted to change to M1 earlier than the 4K mark, but seeing how high the copper wear is in these engines, why waste money tossing good M1 after 1500 or 2000 miles? So the reason boils down to cost.


Why is M1 so highly regarded yet isn't recommended by many in brand new engines?
Only one reason---cost.
My owner's manual doesn't mention "break in " oil. I'll call the dealership Monday to find out what the service dept says.

Right now I'm leaning towards going with M1 @1k miles, then M1 @4k miles or 4 month OCI. Wally World's price with a Supertech filter is $32.74.

Soooooooo, for yr I'll be running fresh M1
My cousin is one of the engine test engineers at the GM assembly plant which built the LS1 engine in the Corvettes (and is now building the new LS2 engine for the C6, plus they build the LS6 that is in the Cadillac CTS-V and the truck motors)

This is a response from him to an email I sent him a while back in regards to engine break in procedure for the Corvette's LS1:


Every engine is cold tested.

Vette engines (for manuals) are also balanced on a hot test stand, using
natural gas. It's not really a hot test, it only runs long enough to take
unbalance readings, usually less than a minute total.

Alot of pre-production (proto, pilots) and start-of-production stuff is
dyno tested, especially if there is a major model change (design change),
new technology on the engine, etc. This is not for break-in but to
double-check quality. These tests are a combination of 20-minute dyno
(loaded) and 10-minute non-loaded, running gasoline.

Every vehicle gets a dynamic vehicle test (DVT) at the end of the vehicle
assembly line. It's basically about a 5-minute (maybe more?) vehicle dyne,
and they check everything you can think of, not just powertrain.

Most engines are only fired up for the first time at DVT.

Do a search on break in. I believe that is an old myth.

Don't know about most manufacturer's, however, at least for Honda, they do use a special break-in oil.

It is in the owner's manual and the American Honda website:

Why should I wait to change the oil the first time?

Your Honda engine was delivered with an oil that is specially formulated for new engines that have not yet developed their "natural" wear patterns and may contain minute particles from the manufacturing process.

American Honda strongly recommends this special oil be left in the engine long enough for these wear patterns to develop, usually until the first maintenance interval specified in your Owner's Manual, based on your specific driving conditions.

Originally posted by 05corollaLE:
Has anyone experienced a problem from switching to synthetic early in the "break in" period?

Three different vehicles, engines, engine designs, NO problems. This is a myth in my book.
The only real reason to use dino in the first 5,000 miles is cost to you. If you drain the factory oil at 1,000 miles then you should probably run the next batch for no more than 3,000 miles and that is kinda wasting money if you use synthetic. If I used syn I would use dino for the first 1 or 2 short intervals to save cash and then switch over to M1 for good.
Money is a non-issue.

I get my oil changed at Wally World and a M1 change with Supertech filter costs about $28, about the average price it cost to get a dino change at most places.
On my 98 Ford Crown Vic, I changed out the factory oil @ 500 miles and went w/syn 5W-30 M1 and 4 years ago switched to Amsoil 5W-30 syn and it works like a charm. It doesn't leak or burn any oil and it has 79,900 miles on it. I am happy with the syn. oil and it does a very good job as I see it.
from Mobil 1 entitled "Myths About Synthetic "


You should break in your engine with conventional oil, then switch to Mobil 1.
You can start using Mobil 1 with SuperSyn™ in new vehicles at any time, even in brand-new vehicles. In fact, Mobil 1 with SuperSyn™ is original equipment (it is installed at the factory) in:

Chevrolet Corvette
All Porsche vehicles
Mercedes-Benz AMG vehicles
Dodge Viper
Ford Mustang Cobra R
All Aston Martin cars

One of the myths that persists about Mobil 1 is that new engines require a break-in period with conventional oil. Current engine manufacturing technology does not require this break-in period. As indicated by the decisions of the engineers who design these high-performance cars, Mobil 1 with SuperSyn™ can be used in an engine from the day you drive the car off the showroom floor.

Using Mobil 1 will void my new-car warranty.
With the exception of the Mazda rotary engine (Mazda does not recommend any synthetic motor oils), Mobil 1 with SuperSyn™ will not void new-car warranties. Mobil 1 with SuperSyn™ exceeds the API and ILSAC motor oil service requirements of all new-car manufacturers, both import and domestic. If in doubt, always check your vehicle owner's manual or contact your vehicle's manufacturer.

You don't have to change the oil as often when using Mobil 1.
While Mobil 1 has given excellent results in extended oil drain tests, ExxonMobil prefers to remain conservative with oil drain recommendations. ExxonMobil engineers recommend that you can go all the way to the maximum mileage or time frame shown in your owner's manual for oil changes when using Mobil 1 with SuperSyn™. This allows the reserve protection capabilities of Mobil 1 with SuperSyn™ to cover unusual or unexpected driving conditions.

Oil change intervals can be as short as 3,000 miles or as long as 15,000 miles on some new cars. Mobil 1 with SuperSyn™'s high-performance reserves can give you the confidence to go the full mileage or time frame recommended by the vehicle manufacturer. Mobil 1 with SuperSyn™ is especially suitable for the latest vehicles with extended drain intervals or vehicles with oil monitoring systems that vary oil drain intervals.

I need to flush my engine before switching to Mobil 1.
No special preparation is necessary when switching from conventional motor oil to Mobil 1 with SuperSyn™.

Mobil 1 requires a special oil filter.
While ExxonMobil recommends that you use a high-quality filter, you can use the same type of oil filter that you would normally use with conventional oil. ExxonMobil does offer a very high-quality oil filter that is a perfect companion to Mobil 1 with SuperSyn™. The Mobil 1 High Efficiency Oil Filter contains synthetic fibers instead of the typical cellulose filter media. With a 95-percent efficiency rating (under SAE J806 tests for capacity and contamination removal), the Mobil 1 filter is much more efficient than a typical oil filter, removing more particles per pass through the filter. In addition, the synthetic fibers in the Mobil 1 filter have less resistance to oil flow, reducing the potential for the filter to restrict the flow of oil to your engine.

Motorcycles can't benefit from synthetic oil.
ExxonMobil offers three Mobil 1 fully synthetic motor oils for motorcycles:

Mobil 1 MX4T is recommended for on-road, high-performance, 4-cycle sport bikes, which are typically liquid cooled. It can also be used in air-cooled engines calling for a 10W-40 oil.
Mobil 1 V-Twin is a 20W-50 oil recommended for 4-cycle V-twin engines, particularly those that are air cooled and tend to run hotter than other types of engines.
Mobil 1 MX2T is recommended for 2-cycle motorcycle engines that specify the use of a pre-mix, 2-cycle engine oil.

Although Mobil 1 15W-50 has been used in 4-cycle motorcycle engines, ExxonMobil engineers recommend using Mobil 1 Motorcycle Oils, since they have been specifically optimized for motorcycle applications. Be sure to follow your owner's manual for recommended oil and filter change frequencies.

Mobil 1 can't be used in diesel engines.
Mobil 1 with SuperSyn™ will provide excellent service for passenger car and light-duty truck diesel engines (API CF or CD), as well as European diesel cars that require ACEA-quality oils. (This is the oil specification used in Europe and developed by European car companies.)

Heavy-duty truck engines that require API CE, CF-4, CG-4, CH-4 or CI-4 should use one of the products from the Delvac® line – Mobil Delvac 1® synthetic engine oil or Mobil Delvac 1300 Super®. Mobil Delvac 1 synthetic oil can help improve fuel economy, extend oil drain intervals, extend engine life, provide enhanced wear/cleanliness protection and reduce oil consumption. Delvac products can be purchased at a large number of truck stops across America, some retail stores, auto parts stores and from ExxonMobil distributors.

Mobil 1 will leak out of the seals of older cars.
Mobil 1 does not cause leaks. In fact, new Mobil 1 with SuperSyn™ was tested in dozens of industry standard and OEM tests to prove its seal performance. It is fully compatible with the elastomeric materials from which all automotive seals and gaskets are made.

ExxonMobil engineers are wary of conventional oils that tout their use of additional seal-swelling agents. With extended use, these agents can over-soften engine seals, resulting in leaks. More to the point, an oil additive will not rejuvenate worn or damaged seals. The damaged seal may have been caused by a worn rotating metal component in the engine.

If an older engine is in good condition and does not have oil leaks, Mobil 1 with SuperSyn™ provides the same advantages as when used in a new engine. ExxonMobil recommends taking measures to repair the leaks, then using Mobil 1 with SuperSyn™. ExxonMobil also always recommends following the automobile manufacturer's manual for the proper oil to use.

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